Hold it. According to Restore from Backup on New Installation - HA Core - #3 by CentralCommand
If you are looking for a backup and restore process for a core-only installation or to migrate between two core-only installations then you must set one up yourself.
So there is literally no way to migrate a core installation (I have no idea how to “set one up myself”, since directly copying the files doesn’t work, and I got into this to use HA but not to wind up coding it.) I thought I was joking about the “backup” feature being one-way, backup-only, without the ability to ever restore, but according to this guy, who is the only person I’ve found online who actually seems to understand this process, that’s the actual literal truth of it. There is no restore feature.
This is some of the worst design I’ve ever seen. My faith that HA is worth spending time on just bottomed out. It broke through the bottom, and hit a whole new bottom underneath that I didn’t even know existed.
So, once my Mini 9 finally bites the dust, that’ll be the end of Home Assistant for me. People need to be able to migrate their settings to another machine, not be stuck forever on whatever machine they first built their starter system on. Anything else is not practical for real-world use.
Especially as, I don’t mind having to put work in myself on setting up a FOSS project, but the fact that it took me an entire afternoon out of my day to even discover that this problem exists, shows that this is too chaotic and poorly designed an ecosystem to rely on. Every aspect of this seems to be mired in confusion and incomprehensibility.
This is really just extremely, extremely disappointing.
Thinking out loud… maybe I can just clone the current hard drive to an image and spin up a debian machine in vitrualbox and without having to change anything. Still, I don’t think I want to bog my mac server machine down running virtualbox 24/7, that seems inefficient.
It seems like the only practical answer is to enjoy it until my Mini 9 finally crosses the Rainbow 802.1D Bridge and then go back to using electric light switches.