I used to run a relay at home until two things happened. 1) my bank blocked my home internet as it was a listed tor relay node even though it wasn’t an exit node. I just told my wife to use the app and disconnect from WiFi so that wasn’t a big issue. 2) getting called to security at my company as they had some abuse from tor nodes and saw I used a “tor node to vpn to work” and it was pretty brutal. Nothing came of it (because I did nothing wrong) but I obviously stopped running a relay. Just a warning.
The probability of that minor inconvenience is very low and i am going to order Pi's. Today i saw the following news and i don't want this to happen to my country(or any other).
Sure, as long as it meets the minimum requirements you can operate a node. If you are running it at home, I strongly recommend you don't run an exit node but that's up to you. If you want an easy setup, a bootstrap script does exist: https://github.com/mricon/tor-relay-bootstrap-rpi
Pis work well. I used to run two nodes on a Pi 3. It easily maxed out its ethernet bandwidth.