Secure boot must have all kernel modules signed. The system that Fedora uses is a way that builds the drivers from source with every new kernel update. It works, but it can't be modified further.

The primary issue you will likely come across is that the nvcc compiler is not open source and it is part of the CUDA chain. You can't build things like lama.cpp without nvcc and have CUDA support. Most example type projects have the same issues. Without nvcc fully open, you are still somewhat limited. Also the toolchain for nvcc screws up the open source built stuff and will put you back at the train wreck of secure boot. If Nvidia had half a working brain, they would open source everything instead of the petty conservative nonsense stupidity that drives proprietary fools. There is absolutely no room in AI for anyone that lacks full transparency.

The opensource drivers are not included by default (out of tree) so no this is the same scenario.

If the boot files change, you cant just fix the signature. Thats a key feature of public-private-cryptography

This is entirely plausible, but I don’t know if it’s there yet. I’ve long since moved to AMD GPUs so I can’t really fiddle and find out. Give the open source drivers some time to mature.

Until then, you are reasonably safe running Linux with secure boot turned off. I’m no expert on the matter, but I’m not familiar with any ongoing threats to boot loader in Linux distributions. Stick to your official repos to be safest, unverified user maintained sources like AUR and COPR are possibly more likely to harbor security threats, don’t use them if you don’t need to or don’t know what you’re doing. Password your bios and require a password to log in to your operating system. Common sense is a better defense than secure boot.

The last time I had secure boot enabled on any of my systems was several years ago, but yes. At that time you had to enroll the keys both on the initial install and every update. It was such a headache for limited benefits (for me) that I just started disabling secure boot whenever I was setting up a system.

Things might have gotten easier, but I doubt it as he secure boot system is not really under the control of open source developers (for good reason) and the end user can really only choose whether it is enabled or disabled.

The procedure is much hassle free than it looks. Keeping the secure boot on enrolled is a good practice. I read recently that Fedora was approving the sign automatically to be part of the gnome-software. So things may become even easier soon.

No NVIDIA doesnt care about being upstream so until something changes they will be out of tree.

Changed boot files hash, broken Microsoft key, you need to sign yourself.

This is automated though.