Have you tried Fedora Silverblue? It uses OSTree technology to offer many of the features of Ubuntu Core including automatic updating, upgrades that work regardless of power loss, Flatpak confinement for all apps (without any arbitrary restrictions like Snaps), and it's free.
"Silverblue is a variant of Fedora Workstation. It looks, feels and behaves like a regular desktop operating system, and the experience is similar to what you find with using a standard Fedora Workstation.
However, unlike other operating systems, Silverblue is immutable. This means that every installation is identical to every other installation of the same version. The operating system that is on disk is exactly the same from one machine to the next, and it never changes as it is used.
Silverblue’s immutable design is intended to make it more stable, less prone to bugs, and easier to test and develop. Finally, Silverblue’s immutable design also makes it an excellent platform for containerized applications as well as container-based software development. In each case, applications (apps) and containers are kept separate from the host system, improving stability and reliability.
Silverblue’s core technologies have some other helpful features. OS updates are fast and there’s no waiting around for them to install: just reboot as normal to start using the next version. With Silverblue, it is also possible to roll back to the previous version of the operating system, if something goes wrong."
"Silverblue is a variant of Fedora Workstation. It looks, feels and behaves like a regular desktop operating system, and the experience is similar to what you find with using a standard Fedora Workstation.
However, unlike other operating systems, Silverblue is immutable. This means that every installation is identical to every other installation of the same version. The operating system that is on disk is exactly the same from one machine to the next, and it never changes as it is used.
Silverblue’s immutable design is intended to make it more stable, less prone to bugs, and easier to test and develop. Finally, Silverblue’s immutable design also makes it an excellent platform for containerized applications as well as container-based software development. In each case, applications (apps) and containers are kept separate from the host system, improving stability and reliability.
Silverblue’s core technologies have some other helpful features. OS updates are fast and there’s no waiting around for them to install: just reboot as normal to start using the next version. With Silverblue, it is also possible to roll back to the previous version of the operating system, if something goes wrong."
https://silverblue.fedoraproject.org