There is no difference between installing software on a VM and on “bare metal”. The OS takes care of the hardware stuff.

I installed it according to their manual on their website (https://radicale.org/v3.html) which is imo pretty easy. The TLDR is that you first install python3 and its package manager pipx, then you install radicale using pipx and finally you run it as a systemd service. You can just copy their service template. The issue comes when you need to run multiple web services though. Radicale wants to be on the website root (website.com/ instead of website.com/some/path/blablabla/ ) which is not as trivial to set up as the previous steps. They have a template for nginx and apache but you need to kinda know the very basics of one of these to set it up.

Also on debian there is a package so you could technically just apt install radicale and then systemctl enable radicale if you want to avoid creating a service and installing python.

Obviously you need to create a basic config either way according to their manual. At least for password authentification.

I just want an app to backup all the photos from my phone automatically. I use NextCloud for that currently and it works well. But, it’s kinda heavy for what I want/need.

I can recommend using Cloudron but I don’t use Radicale.

Cloudron is in no way a necessity for anyone - it’s simply me being too lazy to keep everything up to date, read all the necessary documentation for all the services we run,etc. Cloudron does all that for me - and I couldn’t be happier. Johannes,the owner, provides fast support (had two glitches with Hetzner DNS over the years) and the amount of Apps is getting wider each year, although I would rather see their range be broader (e.g. a proper Monitoring system instead of yet another project management),but that’s just me.

In theory it’s even possible to create your own apps for cloudron, both for public and private use, but that is beyond my capabilities. It can also be used as a SSO provider and reverse proxy,btw.

I’ve been hoping to find a non-PHP alternative to Nextcloud for a while, but unfortunately I’ve yet to find one which supports my base requirements for the file storage.

Due to some quirks with my setup, my backing storage consists of a mix of local folders, S3 buckets, SMB/SFTP mounts (with user credential login), and even an external WebDav server.
Nextcloud does manage such a thing phenomenally, while all the alternatives I’ve tested (including a Radicale backed by rclone mounts) tend to fall completely to pieces as soon as more than one storage backend ends up getting involved, especially when some of said backends need to be accessed with user-specific credentials.