I think auto update is perfectly fine, just check out what kind of versioning the devs are using and pin the part of the version that will introduce breaking changes.
tofu
Did that as well a while ago and generally it's working pretty good, some services had the possibility to migrate existing accounts to authentik even. But even though it's been pretty reliable so far I'm hesitant to migrate my more critical services behind another runtime dependency.
Cool! Home Assistant has it and I can imagine Nextcloud as well but those are overkill just for that.
Don't have a good guide, but in addition on the thing you plan to selfhost yourself you need to decide where it's supposed to run. In a rented VM from a hoster? There are several ones where you can get a decent VM for a few bucks each month.
Nowadays, Docker (or containers in general) are very popular, as an alternative to directly installing services on the vm. They make many things easier, but it's another thing to learn about when you're just starting - fortunately, there's plenty of guides etc!
I don't know all of the tools, do you mean the tor relay?
On Android or postmarketOS? Very cool regardless!
I think the only thing where you can mix CPU architectures without much problems and doing something meaningful with would be a Kubernetes Cluster, e.g. install K3S across the machines.
As others mentioned, the 3rd gen CPUs are probably using quite a lot of power. I'd get something to measure how much the whole machines draw from the wall and decide if you're fine with that (measure while there's actually something going over the network interface and some r/w operations).
The CPUs should be powerful enough to run most classic selfhosted apps.
Ghost Activitypub support is still in the making unfortunately. You can selfhost ghost already and if you check out the latest version you also have AP, but they said it's not stable yet and might break. Eagerly waiting for them to finish.
Playing information ping pong. We sent them some issue with a lot of information and instead of actually investigating they often dragged on the whole thing by asking for details they should have themselves, taking hours-days to respond etc before they actually did something. We often had to escalate issues via our account manager.
This was all on enterprise support while I was working for a company that paid six figures each month for infrastructure in their data center.
Only know Ionos in DE but I can't recommend it, the support is pretty bad.
You can have the best of both worlds - scheduled auto updates on a time that usually works for you.
With growing complexity, there are so many components to update, it's too easy to miss some in my experience. I don't have everything automated yet (in fact, most updates aren't) but I definitely strive towards it.