I've been sticking w/ very compact units, mainly ThinkCentre M series "Tiny" and Dell OptiPlex "Micro" form factor, which are both practically identical in size. Both use a laptop power supply. You can get current versions for many hundreds of dollars or generation(s) old ones for as cheap as $30 USD. My most recent ones were older 3rd & 4th gen i5 & i7 CPUs but they still blow current Raspberry Pi, etc. out of the water, have M.2 for network, etc. & SATA for storage. A Dell I have that's a generation newer than these adds NVMe too. It's hard finding these small PCs that have multiple Ethernet but I just added a gigabit Ethernet M.2 card to the one.