Get a Mini-PC and put some Linux distro and Kodi on it.
Or even better, get one of the many LibreELEC supported devices (including, as somebody mentioned, a Raspberry Pi 5) and put LibreELEC on it (which is a pared-down Linux with Kodi).
Personally after maybe a decade running successive generations of TV Media Players to play my growing video file collection on my TV, on my latest upgrade I ended up going down the Mini-PC with Linux and Kodi on autostart route (as I used it also as a home server) and am very satisfied with it, though if I wanted to just use it as a Media Player I would've gone with LibreELEC and on of the various ARM SBCs they support (maybe the Pi, maybe something cheaper).
There really is no reason to use closed commercial solutions for this.
Edit: If all you do is consume media on it via Kodi, you can use a remote like this one so it's the same usage experience as with a commercial device, just without the enshittification.
Indeed. Any online store can go under or enshittify.
If you want to stay safe with GOG, download the offline installers for your games and archive them. If you don't you're running the risk of losing some or all of it.
The rule "best avoid situations where you give power to some big company (for whom you as an individual customer are basically a nameless bacteria) over something you care about" is general, not Steam specific.
Fortunatelly GOG has DRM-free offline installers available for download as standard, Steam does not make that option available - at best you can copy and zip existing installations of Steam games and hope for the best (some will work, some will not), and that is a "hack" rather than official supported.
The point being that Steam could make something like DRM-free (or at least phone-home-DRM-free) offline installers available - at least for games whose developers/publishers are willing - and mark that as a feature in the game page in their store for those games, but they have chosen not to do so and remain steadfast in that choice: they purposefully keep customers dependent on them of enjoy their purchases and we're all expected to just trust them, now and forever.
As I said, 4 decades in gaming and Tech have taught me you can't trust large companies forever.