DietPi is an excellent ARM SBC debian distro if you want to run a DIY NAS/media server/Pi-Hole/torrent platform.

They have a great set of CLI tools to cover most common use cases for a headless device. Personally, I found their tooling to be a great introduction to CLI linux. The baseline tools have you covered, but you can start experimenting once are comfortable with linux CLI (and you need to implement some custom solutions).

One cool feature that it has is that logging is done in RAM, thus extending the life of your SD card.

I've been using DietPi since 2018. For a relatively small distro (about ~100K users), they are very active and responsive on their communication channels.