upgrade the UEFI or other hardware-level firmware you need a way to upgrade
Indeed but unless the unit received is seriously flawed (to the point of possibly being exchanged by the manufacturer), no upgrade to UEFI or hardware-level firmware is actually required. Most people who received a computer never even upgrade the firmware. I’m not saying it’s not “nice” to upgrade it but the typical scenario for most common laptop or desktop is that such upgrades are optional.
It is finicky on any distribution because NVIDIA drivers aren’t perfect on Linux nor on Windows.
That being said I’m gaming, in VR and otherwise (using native games, Proton ones, Steam VR, etc), or running local AI models (thus via CUDA) on a daily basis on Debian and have no problems. You can check https://wiki.debian.org/NvidiaGraphicsDrivers but it’s basically just installing the driver like any other package. I don’t have more or less problem than with e.g. Ubuntu. It basically works.