That Fedora as well as openSuse doesn’t like Nvidia, that they supposedly run best on AMD, or is that not true?
My understanding is that AMD drivers are open source and included in the Linux Kernel. Regardless of the distro you choose, AMD tends to be less problematic than Nvidia’s proprietary drivers (though Nvidia has been making some positive steps more recently).
That Fedora as well as openSuse doesn’t like Nvidia,
Not sure what is meant by that. Best guess is it is a misinterpretation of something like “Fedora and OpenSUSE don’t like closed source software” and don’t pre-install closed source software like the Nvidia driver by default."
You must install the drivers manually, but realistically, that is mostly just a small difference in convenience not performance or capability. Also worth noting that, both of the gaming oriented distros you mentioned earlier (Nobara and Bazzite) deliberately chose to build on Fedora.
I don’t know, I don’t have any firsthand (or secondhand) knowledge about that. But I assume if there is substantial truth to it, there would be publicly available empirical evidence and specifics to support the claim, and whatever innovation would eventually be upstreamed or adopted by other distros (if it were a substantial improvement and didn’t have negative tradeoffs).
In my experience, at any given moment there are usually a few distros getting hype for being “optimized for gaming” or “optimized for Nvidia” or being theoretically “Faster”, in my experience any differences are usually modest and often not very perceivable or impactful in practice, and these ‘flavor of the month’ distros rise and fall in popularity/hype every few years. Maybe I’m just being a little too jaded but I tend to tune out the ‘flavor of the month’ distros and circle back to them if they are still around and relevant once the hype subsides. I’ve kind of perceived Cachy to be in that category but I could be dead wrong about that, it isn’t something I’ve looked into, just an unformed impression. It’s definitely a generalization, and for every generalization there will be exceptions. So take my impression with a grain of salt.
If you want to try a few different distros and see what works for you, on your own hardware Ventoy is a useful tool that makes that easier. In my eyes, experimenting and exploring is a big part of what makes Linux fun.