A cheap laptop might also be worth considering? Built in UPS that way, and sometimes UPSes have a large standby power usage. Would support a couple of bus powered drives as well.
Main drawback is no recovery if the battery drains fully.
Rustdesk, so I can remote into my main computer and the others I manage.
PWAs For Firefox.
And that's about it.
I use Debian BTW. (Was on Fedora but killed it when there were sound issues, turned out to Rustdesk at fault. Can't do Mint as it boots to black screen.)
Maybe have a look in https://www.radio-browser.info/users
I haven't had a play with it yet.