I actually like Debian’s slow update cycle, as I don’t want to be bothered often with setting up my system again.

I've been there too!

Updating to a new version is such a chore: you have to follow the news, then wonder how long to wait before updating, then you have to set aside at least a few hours for the actual update (well, for fixing what may go wrong - not that stuff actually goes wrong, but you still set aside some time just in case).

The solution to this is in the exact opposite direction you'd imagine.

For a few years (since last time I got a new PC), I've been running a rolling distro (tumbleweed *) and... it's been great: no big updates, just incremental ones.

If anything breaks (and it never happened to me: there has been times where errors prevented the system to update, but never has it broken on me), you just boot the snapshot before the last update and try again in a few hours/days.

I want something as close as “set it and forget it” as possible.

That's nixos :) It takes a long time to "set" (and you never really finish doing it) but you can switch to a new PC at any time and have your exact system on it (bar what the few things you have to change to account for the different hardware, of course).

* I hear that with arch&co you actually have to follow the release notes as sometimes there are manual tasks to do - it's not so in tumbleweed (at least, as much as i know and as far as me experience goes) - IDK about other rolling distros (or debian testing/sid)