On the tech side of things, I'm looking at a raspberry pi 4. Apparently RAM is not a huge issue so 8 GB seems adequate. On that note though, would a PI 5 with 8 gb of RAM be better? The 16 GB is pricey. The docs are for a pi 4.

https://ethereum.org/en/developers/tutorials/run-node-raspberry-pi/

Considering your needs, Raspberry Pi 4 with 8GB RAM should suffice for now. Upgrading to a Pi 5 with 8GB RAM might not provide significant benefits unless you have specific requirements. Stick to the Pi 4 as per the documentation provided.