Did you try the Linux portable version of GZDoom, or Doomsday?
Before making my final switch to Fedora 39 (distro upgraded from F38 through Konsole), I was considering Debian 12 because I thought that, being one of the oldest active Linux distros, Debian might be best for me, that is until I found it severe lacking of software updates which would be a major problem for both gamers and developers alike.
This is exactly the reason why I chose Fedora 39. The only problem I currently have with Fedora 39 is, for some unknown reason I simply can’t fathom, the Flatpak release of OpenTyrain had begun crashing on me after using upgrading the distro from Fedora 38 within Konsole. Fortunately for me however, the Snap release of OpenTyrian still works flawlessly.
ProtonDB says BG I and II enhanced are both native.
So does Steam. The bare minimum of Linux OS is Ubuntu 18.04 or equivalent, so your all good.
Many online game retailers will sell games keys for different gaming outlets while some will sell keys for multiple outlets. For example, GAMiVO.com may sell Steam keys for a specific game you may want while Humble Bumble may sell both Steam and GOG keys for the same game you may want.
GAMiVO.com also usually have good deals on games as well. The last few games I purchased online was from them.
I’d say go with whichever Linux distro you feel most comfortable with. I would first highly recommend trying each as a virtual machine first to test which one you prefer. This way, you still can game while trying out each of the Linux distros all in different VM’s.
Even though Fedora is one of 3 Linux distros Red Hat uses as a testing bed for their professional Linux distro, I find Fedora is a very stable and somewhat fast OS that doesn’t sacrifice standard Linux security, which is exactly why I chose to replace Windows 10 22H2 with Fedora 38 originally, but distro upgraded to Fedora 39.
I was going to originally install Debian 12, especially since Debian happens to be one of the oldest still active Linux distros which to me meant it’s a reliably stable and secure OS. Only problem is, the Debian team sacrifices latest package availability over stability, which makes it unsuitable for gaming purposes for me.
I have tried Kubuntu (which is Ubuntu-based; Ubuntu is Debian-based), and found it to equally be as good as Fedora, but is rather slow at providing Kernel and KDE Plasma updates but it is solid, stable and secure.
I also tried Linux Mint Cinnamon (Ubuntu-based) and found it to also be as solid, stable and secure as Fedora, Debian, Ubuntu and it’s flavors.
Whichever distro you choose to replace Windows with is up to you, but do be well aware that, not all games that was built for Windows will run with WINE (which is a Windows compatibility layer for Linux). Genshin Impact is playable and many emulators has been natively ported over to Linux.