I am already on Fedora Kinoite. Not sure if their immutability model is actually suited for rolling Distros though:

• OS packages are traced by OSTree
• updates come from another repo using OSTree (afaik). So you have a "wanted" "vanilla Fedora KDE" image on their servers, and your client has older packages, downloads just the diffs
• the OS does atomic updates. I guess this can't be done differently. Updating works fully in the background, a new system image is built. If you dont like it, sudo ostree admin cleanup 0. Btw wheel can do rpm-ostree stuff without a password prompt.
• when rebooting, without any second of delay, you boot into the updated system. In grub you can see both options though, if you something may break
• as the system is image based, you can rebase to any other system images. These are like Docker/Podman images.

Its a really superior technology and the best overall solution. I was mind experimenting with an only traced system that is not immutable but uses OSTree to manage updates. Only when something breaks you would create a new clean image, or rebase. As most updates work normally since forever.

Because in the process of generating the image, locally the complete OS is build on every update. Not downloaded. But copied etc. This takes a lot of resources, which works fine on monthly updates like on Android, but not so well on daily rolling updates.

To "Linux mint does not require OStree". Rpm-ostree or apt-ostree not. But ostree I think yes. It may be stable and all, but what if its not? And you dont want to reinstall everything? There needs to be a way to reset the system to work again. All rpm-ostree does is remove "it works on my machine though" bugs. Its the only thing newcomers should use.

You are not meant to add tons of RPMs to your system, but you can. Updates can be done in the background, no problem. So you could literally "layer" (thats what its called) any huge piece of software, that doesnt work locally. You can add proprietary drivers, install media codecs and all.

Various ways to make media playback work on RPM Firefox

UBlue, and awesome project creating custom OS and Distrobox/Toolbox/Docker/Podman images for things like Arch+AMDGPUpro Drivers for Davinci resolve. They create their custom versions of the distros with patches for Asus, Framework, Surface, and all out of the box, secured modifications that are reproducible

Ublue really shows the potential of rpm-ostree. Use Fedora as base, to kernel mods, layerings, replacements how you like, and ship the "working out of the box" image for exactly your hardware. Its brilliant.