My TL;DR guide for self hosting on a Pi.
Get Pi Install DietPi Install Docker, Docker-Compose browse the LinuxServer.io fleet create docker-compose file with needed 'stuff' (letsencrypt, NextCloud, etc) run.
A pi4 4gb should run NextCloud plus other "stuff" without an issue (Mine has a bunch of *arr's). As other's mentioned, storage might be an issue. My Pi's all point back to a NAS for file storage/serving.
