Debian

It may be possible to create a UI using a monitoring program like Zabbix.

You could create a custom dashboard that displays all the stats that they need to see.

This of course would be for viewing only, not controlling the schedules, retention etc

Markor on Android and Obsidian on Desktop.

All synced with syncthing

Look at Mikrotik. Very affordable and extremely powerful. Only do this though if you know what you are doing with networking

Can you send you docker-compose file?