What to mine with new rasberry pi4 - 4 gigs ram?

Can we run external GPU cards on it now?

Are there any good tutorials for newbs on tuning  a full node to use max memory/cpu/internet bandwith  if you have a server dedicated to  just being a full node. I've read the main one, but curious what options make the most difference. What upgraded hardware woudl make the most difference to validate more transactions...