You get full difficulty customization at the start, going from super casual/no enemies to hardcore ironman with heavy enemy presence. They were a bit late pushing some updates, vs Steam, but I can't really fault them considering how small the studio is. That said, they did continue to push updates to GOG throughout the entire EA period and, as you can see today, they did release 1.0 update at the same time on both Steam and GOG so I appreciate that.

For me this game was very close to being 2021 GOTY (which was taken by Forgotten City, another indie gem), the gameplay loop is very addictive once you get past the initial learning curve (especially if you haven't played a lot of similar survival games, which I didn't).

I played it when it came out (EA) last year. Back then surviving was easy. Exploring and progressing was hard. In the desert there is no thermo-regulation. During the day you have to worry about heatstroke. During the night about cold. No problem then, you think? ''I'll build up my shelter, craft a straw hat, prepare several water bottles and go out when I'm ready!''
That will increase your chances, but during exploring you may come upon hyenas, and what's worse, those sandworm things.
My biggest complaint, and those of others, if I recall, was that each day passed +1 sandworm was spawned to attack you. I think they patched that one ''feature'' out very fast.
But I'm not sure what the current state is. I played for awhile during EA, never patched it and was surprised that is now out of early access.

Is it true that this game requires GOG Galaxy to play?

You don't need the client to play the game but for achievements and cloud saves.

It reminds me more of a Stargate than Dune.

Feels nothing like Dune, except oh wow, it's a desert.

Feels more like it was inspired by Stargate tbh, but then you'd have to play it to see what I mean.

Sand + those large worms made me think of Arrakis.

It is good if people who have actually played this tells what the gameplay is like and reminds you of so have some plusses for that.

Not anymore. They fixed this issue with the latest update.

Worm + Sand + totally not Fremen = Dune

Pyramid + Font = Stargate

Does it allow to say that you want challenging combat but don't want to worry about survival aspects?

Setting Stats to Easy and Aliens to High at the beginning of a new game will allow you to focus more on other aspects of the game.

From personal experience, playing it on "High", I found that it is more difficult to die than staying alive. Difficulty in this game is based on numbers and timers. There are fixed enemy-spawn intervals and max number of concurrent enemies, temperature rises faster, injury or poison does a little more damage, water and food level has to be monitored, it isn't possible to run around in circles exploring the desert but follow the shortest possible path from one shade source to the next, and certain things have to be done in a different order. It is almost impossible to starve or run out of water.

Everything in this game is static, props and items have been hand-placed, they have their fixed spawn-intervals, so the same stone or item can be found in the exact same spot. It's also easy to get around without getting lost. For instance from the first building to the Yukka plant, Yukka to Palm tree, Oasis, from Monument to Monument, to Canyon, etc.

Enemies aren't difficult to kill either, again thanks to static numbers, spawn direction, intervals and maximum number of concurrent enemies. No need to learn an attack pattern or develop a strategy to approach a fight. Putting a fence around an oasis, placing a trap in the direction the enemy will spawn or approach from, in case the spawn-point is further off and invisible, activate the trap and the sandworm is history. During exploration the usual, shooting or hacking away at it until it dies, usually also does the job.

If you are just looking for a relaxed survival-like-builder with a clear goal, without getting overwhelmed by thousands of different tasks, getting lost or swamped by enemies, you will certainly like this game. If, on the other hand, you are looking for some real challenges, you should look for other games.