I have no particular suggestions for the Pi, but for the x86 box I’d go headless Arch, install docker and go from there.
Also, I’d personally suggest switching to something that’s not Manjaro. Arch has an install script now which I really like, but there’s also distros like EndeavorOS that don’t have a history of letting thier SSL certs expire multiple times like Manjaro does…
It’s getting up there in years but I’m running a Dell T5610 with 128GB RAM. Once I start my new job I might upgrade cause it’s having issues running my MC server.