When I say minimalist, I mean those low-bandwidth text-UI Embedded Operating Systems (mostly Linux) that are only intended to run Servers, or IoT Smart-Home setups, or something similar.
For example, Ubuntu Server.
There's lots of them out there, and I want to know which would any of you recommend.
I want advice from someone who's been using Pi-Hole for a very long time (if that's possible).
The question asked for the "best" minimalist OS. In my opinion, the best option would be a version of Linux supported by us. Users have installed Pi-hole on a number of unsupported OS's, but this involves workarounds and potential breakage with the next Pi-hole update.