I tried one time to make my own personal instance https://potato-guy.space/, that ended because I forgot my ssh keys when i distrohopped, but I could make some suggestions.

• Get anti-bot protection, like cloudflare (or something more privacy friendly) AND something like anubis or a nginx plugin.
• Don’t make it on your network if you don’t know what you’re doing, put it on a rented VM on the “cloud”, the chance of someone breaking into your network because you misconfigured something, if you don’t know about network security, is above zero and horizontal hopping in a network is feasible.
• A raspberry pi is enough, just use some optimzed settings and use the picture server settings to use postgresql too, just create a new database on postgresql and hook that on, it will be more cpu and ram friendly.
• If you really want it on your network, double check and triple check every router configuration, put it on a virtual network, inside a VM, outside your own network so horizontal attacks don’t happen.
• Edit: Also, use btrfs with compression enabled for the postgresql database, it will make the database faster as the read and write ops will be 2x (with lzo, almost no cpu usage) to 3x (with zstd, but with more cpu usage) faster.

This is the docker-compose config for lemmy: https://github.com/LemmyNet/lemmy/tree/main/docker

This is the tutorial for it: https://join-lemmy.org/docs/administration/install_docker.html

Some drama happened in the past on those docker configs, check all and put your domain where needed.