If you're on Nvidia, go with something like Nobara or Bazzite. Nvidia's linux drivers are in flux right now (esync/wayland), you want a distro that is aggressively chasing the latest drivers but lets you take a step back with atomic updates.
You can have most of the settings pre-loaded in its config file. I mostly let it do my preset -f, or when that fails do a -F to see what encodings are available.
I have a Debian 12 install on a 5GB partition (btrfs compression is magic), and the rest is exfat. It has rEFInd as the bootloader, should be pretty good at detecting and running other OSes with bootloader problems.
Try rEFInd. It's pretty good about detecting OSes and auto-populating its menu, and it has a pretty easy conf file format otherwise. Installing the refind debian package mayybe will also register it with the system firmware, I don't recall. If not, it can be set up with efibootmgr (which is not the most pleasant program, sadly).
Considering that it has a 2020 firmware, and is built by "to be filled by OEM", my completely unfounded wild guess is that the system firmware has broken legacy boot support. From other posts here, I gather you're using a legacy dos-style partition table. Try installing again with GPT/EFI instead.
This. A fresher Proton-GE is also going to come with a newer DXVK, the DirectX to Vulkan translator.
The other part of your equation is "what is the Nvidia driver version?". Dunno if Fedora has the E-sync capable version 555 yet.