Rpm-ostree works perfectly well for many users. Flatpak is not production ready, but if you do background updates and not that often, you can totally just layer everything you want.
Immutable is not cutting edge, is simply a traced, resettable, secure system. You can reset it with one command. But you can also install as many native packages as you want, simply that updating will take a bit longer then. But updates are done in the background, I dont know if by default, but there is a systemd service.