Debian is fine and you can follow many tutorials (Ubuntu tutorials also usually work as the difference isn’t big).

Proxmox is my number one choice. It’s based on Debian, and has an excellent, extremely straightforward web UI for managing virtual machines and LXC containers.

Your computer very likely doesn’t need a special distro for low end devices yet. A common distro like linux mint will do fine, and that’s probably the best choice if you’re new to linux.

Edit: if you only want to host stuff on it, and nothing else, maybe that yunohost people recommended can be a better choice

I’m a complete noob

selfhost files with nextcloud and imich

You should definitely use YUNOhost :)

FreeBSD - it won’t be easy, but I’ve been a BSD guy at heart for decades… You will learn a lot and eventually be able to create better systems, but it will be years before you should risk putting anything important on a system - as a noob you have a lot to learn the hard way. Once you think you know FreeBSD you should try the other BSDs, and things like gentoo linux: you will really learn how this works.

You can follow the advice of the others and get a system going sooner. It isn’t a wrong choice, but you won’t learn as much and if something doesn’t work the way you want you are stuck since you can’t dare change anything. As such I have to advice against it despite all the time/effort my advice will cost you.

Yunohost.

if you want to self host and not open to the internet, alpinelinux is small, install docker and run your containert there, low footprint.