I have a unused RPi4 (the 8Gig one) running DietPi.
I did use it as a playground but ever since I am renting a Hetzner machine for (playground) stuff that I want web accessible, I don't have particular use for the Pi.
I am currently running (outdated) Home Assistant on it but there isn't much I can connect it with (yet, getting the flashable/compatible ikea smart lightning zigbee? bridge thingy is on my bucket list).
Obviously I do have a pihole there.
Shoot me any other ideas I could run there.
Some kind of monitoring of my rented infra would be cool (I already have uptime kuma on the dedi hetzner box). One idea I had was if there are some OSS security scanning "daemons" I could use on to monitor my other infra.
You can setup a tunnel from your Hetzner VPS to your home with say Netbird and then run stuff that would be a bit to expensive to run on rented hardware. Like say Nextcloud, Matrix or game servers, on your RPi while still having them web accessible thanks to the tunnel.
I rent dedicated machine so the HW I have is the limit - I pay the same rate every month, no matter the usage, so with the bit outdated but still performant Ryzen 5 3600 and 64GB of RAM I was very happy to throw minecraft/zomboid/vallheim servers at it and few more services, aye aye;)
Though the possibility of tunneling services out from the RPi is something I am aware of, but except for stuff that would benefit from video HW accel there isn't much that would be better to run on the RPi instead of on the server directly.
Cool, but I'm guessing that ain't especially cheap right? I pay $60 a year for 4 cores and 8 GB RAM (400 gb storage). Which I consider a pretty OK price. $5 a month.