Myself right now I'd probably take it with me - in fact that's that I'm planning to do in a couple of months - but it sounds like my needs are a bit less than yours, and i can do some stuff just over LAN and on the 'server' (which is also a laptop) itself.
For more, I think I'd also ask a friend like you're thinking.
I did that before with a relative - just had to ask them to restart the server every now and again!
About trusted encryption keys, I did it with a simple password for boot encryption, that my relative knew, so in the event of theft it'd still be hard for thieves to get anything; but after boot I'd ssh in and unlock the second disk with my own password, then start up the services.
I'm liking it. I've had no problem with the Android app, but then I don't use it a lot, nor do my 10k pre-shrunk photos compare to some people's collections here.
My only complaint is that two accounts don't share great if you want to share face data etc. or to have a shared album show up in each others' timeline.
Edit to add: Also because it lacks editing, I think my new workflow is going to have to be keep the photos separately still and edit/sort them my old way, then put them back in an external folder. I still want to do external folders generally because I still want my photos organised my way on the file system, but I was hoping to gradually sort/delete/edit in Immich to make the workflow more relaxing. Maybe I'll still do some of it - deleting and I think it can rate - but I haven't worked that out yet.