...because GOG lacks a search filter for dubs, here are 205 (likely not all) store products with Italian voiceovers (some are bundles where only some of the games are dubbed):

7th_legion
act_of_war_gold_edition
alan_wake
alien_isolation_collection
amerzone_the_explorer_legacy
anno_1404_gold_edition
arcania_fall_of_setarrif
assassins_creed_directors_cut
asterix_obelix_xxl_2
asterix_obelix_xxl_3_the_crystal_menhir
asterix_obelix_xxl_romastered
atlantis_the_lost_tales
baldurs_gate_2_enhanced_edition
baldurs_gate_dark_alliance
barrow_hill_curse_of_the_ancient_circle
batman_arkham_asylum_goty
batman_arkham_city_goty
batman_arkham_knight
batman_arkham_origins
bee_simulator
beyond_good_and_evil
beyond_two_souls
biomutant
bioshock_2_remastered
bioshock_infinite
bioshock_remastered
blade_of_darkness
blade_runner_enhanced_edition
blades_of_time
bloodrayne2_terminal_cut
bloodrayne_terminal_cut
broken_sword_2__the_smoking_mirror
broken_sword_3__the_sleeping_dragon
broken_sword_5_the_serpents_curse
broken_sword_directors_cut
brothers_in_arms_earned_in_blood
brothers_in_arms_hells_highway
brothers_in_arms_road_to_hill_30
call_of_cthulhu_prisoner_of_ice
call_of_juarez_bound_in_blood
children_of_silentown
civcity_rome
close_to_the_sun
codename_panzers_phase_two
commandos_ammo_pack
commandos_2_hd
convergence_a_league_of_legends_story
crookz_the_big_heist
cyberpunk_2077
cyberpunk_2077_phantom_liberty
darksiders_genesis
darksiders_ii_deathinitive_edition
darksiders_iii
darksiders_warmastered_edition
days_gone
dead_space
deponia
deponia_2_chaos_on_deponia
desperados_wanted_dead_or_alive
detective_gallo
deus_ex_human_revolution_directors_cut
deus_ex_mankind_divided
die_by_the_sword_expansion
dishonored_2
dishonored_death_of_the_outsider
dishonored_definitive_edition
doom_3
dracula_origin
dracula_trilogy
dragon_lore_the_legend_begins
dungeons_2
dungeons_3
dying_light_definitive_edition
enclave
escape_from_monkey_island
expeditions_conquistador
fallout_3_game_of_the_year_edition
fallout_4_game_of_the_year_edition
fallout_new_vegas_ultimate_edition
fear_3
fenimore_fillmore_the_westerner
full_throttle_remastered
giants_citizen_kabuto
goodbye_deponia
grand_ages_medieval
grim_fandango_remastered
gylt
heavy_rain
hextech_mayhem_a_league_of_legends_story
hitman_absolution
horizon_zero_dawn_complete_edition
indiana_jones_and_the_emperors_tomb
journey_to_the_center_of_the_earth
just_cause
just_cause_2_complete_edition
kane_and_lynch_dead_men
kane_lynch_2_dog_days
legend_of_kay_anniversary
lego_batman_3_beyond_gotham
lego_dc_supervillains
leisure_suit_larry_magna_cum_laude_uncut_and_uncensored
mafia
mafia_definitive_edition
mafia_ii_definitive_edition
mafia_iii_definitive_edition
mdk_2
men_of_valor
metro_2033_redux
metro_exodus
metro_last_light_redux
middleearth_shadow_of_mordor
mirrors_edge
moto_racer_2
necronomicon_the_dawning_of_darkness
necrovision
nikopol_secrets_of_the_immortals
overlord_ii
overlord_raising_hell
perimeter
pilot_brothers
pizza_spy
post_mortem
prey
prince_of_persia
rayman_3_hoodlum_havoc
realms_of_the_haunting
red_faction_guerrilla_remarstered
return_to_mysterious_island_2
rogue_trooper
rogue_trooper_redux
ruined_king_a_league_of_legends_story
rune_classic
saboteur
screamer_4x4
shadow_man_remastered
sherlock_holmes_nemesis_remastered
sherlock_holmes_the_awakened_2008
sherlock_holmes_versus_jack_the_ripper
silver
simcity_4_deluxe_edition
slave_zero
sniper_elite_berlin_1945
song_of_nunu_a_league_of_legends_story
space_colony_hd
spongebob_squarepants_battle_for_bikini_bottom_rehydrated
stalker_call_of_pripyat
stalker_clear_sky
star_wars_dark_forces
star_wars_dark_forces_remaster
star_wars_jedi_knight_dark_forces_ii
star_wars_starfighter
star_wars_the_force_unleashed_ii
star_wars_the_force_unleashed_ultimate_sith_edition
still_life
still_life_2
stranglehold
stronghold
stronghold_crusader
stronghold_crusader_2
swine_hd_remaster
syberia
syberia_2
the_black_mirror
the_bureau_xcom_declassified
the_curse_of_monkey_island
the_dig
the_elder_scrolls_v_skyrim_anniversary_edition
the_evil_within
the_evil_within_2
the_feeble_files
the_mageseeker_a_league_of_legends_story
the_moment_of_silence
the_talos_principle_gold_edition
the_town_of_light
the_witcher
thief_definitive_edition
thimbleweed_park
timeshift
tomb_raider_anniversary
tomb_raider_goty
tomb_raider_i_to_iii_remastered
tomb_raider_legend
tomb_raider_underworld
tropico_reloaded
tropico_3_gold_edition
tropico_4
tropico_5_complete_collection
tropico_6_el_prez_edition
two_worlds_2_epic_edition
ufo_robot_grendizer_the_feast_of_the_wolves
uncharted_legacy_of_thieves_collection
voyage_journey_to_the_moon
warhammer_40000_space_marine
wavetale
wolfenstein_ii_the_new_colossus
wolfenstein_the_new_order
wolfenstein_the_old_blood
xblades_hd
xcom_2
xcom_chimera_squad
xcom_enemy_unknown_complete_pack
xiii
xiii_century_gold_edition
xiii_remake
z

Detective Gallo and Pizza Spy are made by an Italian developer.

Z isn't a typo, it's a game: https://www.youtube.com/watch?v=Tpqf_OqD_iE

Thimbleweed Park has a quality fan dub hosted by Gugames, who also made The Will of Arthur Flabbington:

https://www.gugames.eu/twp-italian-voiceover/

Children of Silentown is made by Italian devs and has nice Italian audio, but only for the intro, the rest of the game is not voiced in any language.

Thanks, I will add it to the list. Strange that they didn't mark it for Italian on the store page.

Commandos Behind Enemy Lines and Beyond the Call of Duty both have italian voice acting.

Also the new Tomb Raider remaster has the italian voice acting for the TR 2 and 3 I believe.

Myst V: End of Ages lists Italian audio (and many other languages), but I cannot find examples of playthroughs other than English.

I only found Commandos 2 HD Remaster. Were the first two on GOG?

In the store they are both part of "Commandos Ammo Pack". They just appear as two distinct games in the library.

What One_of_Many said. The two are sold as a bundle, pretty much. Also, Dracula 1 (The Resurrection), 2 and 3 all have italian dubs as well. Voyage: Journey to the Moon is also part of the club.

Great, added them all. Let me know if you find any others.

I believe Alan Wake, Mirror's Edge and The Talos Principle all have italian versions here on GOG as well. That's probably all I can dig out from my collection that isn't on the list already.

Edit: Also the Tropico series. I know Tropico 3 has the Italian version, but I haven't played the rest yet to confirm if they have it (they are listed as having italian audio on the store, though). Well, I say "italian version" but I think it's mostly the radio that comments on what you are doing which is translated, it's not exactly a dialogue-heavy game otherwise ( and I can't remember if there is any other form of narration, outside of the speeches you can give to the nation for election day).

I saw a complaint on the Steam forums, from shortly after release: So I guess they initially listed it as containing audio in Italian and three other languages, but then removed that info because users like the one cited above thought it misleading?