I have a couple friends like this over the past few years that I just built their server and taught them how to install updates on the terminal (or write a maintenance script for them to run) and how to open a port if I need to fix something remotely and it has been great.
Also, Depending on the user once it’s set up I usually recommend either Portainer or Cockpit are more than enough with watchtower to keep things up to date. If that is too much I usually just suggest a Synology/qnap or TrueNAS/unRAID for roll your own.
ETA: Cockpit also has a web based terminal and can execute package manager updates as well.