If you’re already running Pihole, I’d look at other things to do with the Pi.

www.adafruit.com has a bunch of sensors you can plug into the Pi, python libraries to make them work, and pretty good documentation/examples to get started. If you know a little python, it’s pretty easy to set up a simple web server just to poll those sensors and report their current values. Only slightly more complicated to set up cron jobs to log data to a database and a web page to make graphs.

It’s pretty straightforward to put www.home-assistant.io in a docker on a Pi. If you have your own local sensors, it will keep track of them, but it can also track data from external sources, like weather & air quality. There a bunch of inexpensive smart plugs ($20-ish) that will let you turn stuff on/off on a schedule or in response to sensor data.

IMO, Pi isn’t great for transport-intensive services like radarr or jellyfin, but, with a Usb HD/SSD might be an option.