I know there are some old school console gaming channels on Twitch as of now (mostly Speedruns, though) but I haven't seen a single one dedicated to retro DOS or Amiga games. Have I just missed them or is there really no one making these kind of streams?

Lazy Game Reviews occasionally streams Dos games.

Thanks for the link. But it seems like there is really not much interest in these kind of things. Also, there are way too few Let's Plays of old (computer) games on Youtube. A bit sad that there are loads of games where there is no coverage at all and some immensely popular games that have so many videos that you would need months to watch them.

Maybe you would even get more viewers with old DOS games than with just another MOBA channel added to the already gigantic selection - who knows. At least there's not much competition that's for sure :)

I don't know about live channels but there are some very interesting channels with pre-recorded coverage.

Ancient DOS Games has interesting overviews of DOS games and how to set them up in DOSBox as well as some general information on other aspects (sound settings etc.)

Mau1wurf1977's channel covers hardware and general concepts rather than individual games. He's currently doing a series on making a "time machine" for running games natively under DOS on real legacy hardware with modern components swapped in where possible--notably including a floppy emulator addon that uses a standard USB flash drive for storing disk images (which the computer then sees as a real floppy disk).