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/

The Raspberry Pi 4 with 8 GB of RAM should be sufficient for your needs. Upgrading to a Pi 5 with 8 GB might not bring significant performance gains, especially considering the price jump to 16 GB. Stick with the Pi 4 for now based on the provided documentation.