I use Obsidian with self-hosted live-sync from here: https://github.com/vrtmrz/obsidian-livesync/

Basically you have a couchDB hosted in your homelab to store your obsidian data and then the obsidian self hosted live sync plugin that runs on your devices connects to your self hosted database and sync your notes there in an optimized. I tried both this and sincronizing via github and I prefer this, because is faster and less intrusive

A mix of cost (questionable), education (less questionable) and coolness (not questionable)

LLDAP is the simplest and covers most basic needs.

A better GUI for portainer that support app stores and stuff like that. Something like a self hosted app store based on docker compose, easy to install, easy to maintain and configure. And with reverse proxy support for containers and app. Good UI/UX is hard to find here. Closest I found is runtipi.io but still misses some details and options for running apps.

I myself am trying to build something like but having a hard time coming up with a sufficiently good design and UX (for my standards)

Can’t you use obsidian for that ?