I tried earlier today and I had no luck actually getting an instance running
It would help if the explanation was specific to a raspberry pi
This is the one I use to host on a vps. No clue on it’s deployability on a pi.
https://github.com/ubergeek77/Lemmy-Easy-Deploy
It’s auto installs and updates. Just need to forward the DNS for your instance to whatever domain name you like. It’s pretty straight forward from the documentation.