Sure, and that's only recommended if you know your way around Kubernetes. I just wanted to illustrate that it's possible to host a k8s cluster with some workloads for 2.5€ per month.

You can always skip the Kubernetes overhead and use plain VMs.

Obviously you can't expect too much from a single vCPU at that price, but as an example, I had the above setup plus miniflux (feed reader), Postgres, Maddy (mail server) and Nginx for a few static sites, all on the cheapest instance. It was mostly fine, apart from occasioal stutters.

The amount of time and the opportunity cost involved in "knowing your way around Kubernetes", might as well just pay for Slack.

Hetzner small cloud instances mentioned are insanely performant. They don’t seem to limit small instances like other cloud providers do. So you can do around 160MiB / s of disk writes and 1gbit network, for $2.5/month.