You mean Kinoite. And the same team that does Bazzite also has Bluefin or Aurora for non-gamers that are Silverblue/Kinoite with extra drivers and codecs and such. Highly recommend any of the 3 between Bluefin/Aurora/Bazzite. They’re also super willing to help out with issues in their Discord or through Github.
It does exactly what you’re asking. Its like Nvidia Shadow Play or OBS. Constantly records so you can hit a button to save things as they happen.