Any reason you're avoiding the Raspberry Pi or other arm based SBC's? You will lose some performance, but most of them are more than capable of running a node and bisq and lightning. No you're not going to have the raw performance oh what year looking at now, but they are inexpensive and they do work.
-Dave
I've seen people mention ARM TrustZone pose some similarity with Intel Management Engine, where they have concern it could weaken security or even used as backdoor.
As far as I know and I am probably wrong, they never fully supported it on the Pi. So I don't think it's much of a worry.
You also have things like the RockPro64 and others that are based on different but similar hardware.
There are also a lot of industrial SBC PCs that do not have any of the IME stuff but they are far from cheap so you would probably be better off getting one of the machines that @af_newbie mentioned.
You can also still find older boards / CPUs out there that will work, but now you are putting decade+ hardware into 24/7 production.
-Dave