Not sure about this project, but Pi Hole (which is very similar and likely covered under your "stuff like this") has updating built in.

Updating pihole is as simple as: pihole -up

Easy enough to cron up.

So, idiosyncratic in that it's not "apt update", but also pretty nice that it's all self-contained.

A lot of projects are also now available as docker containers, so you can just pull down the latest container version, currently my preference for home hosted things.