Several years ago I bought Raspberry Pi 3. It was a nice toy, but it was very slow and almost impossible to use, so it didn’t stick. Recently I bought new Raspberry Pi 4 because it has much better hardware (especially 8GB RAM option).
Idea was to use it as a mini-server and run pi-hole on it. In general, it was a success, after installing raspbian, I installed docker on it and run pi-hole docker installation. Few tweaks were required to configure my router to update DNS, but I’m still not happy with the result. My router doesn’t allow to customize DNS servers that are distributed via DHCP, so all clients get default DNS which is my router, and router uses Pi Hole. As a result, in pi-hole I see only 2 clients - localhost and my router.
But still get a lot of benefits by blocking most of the ads on most of my devices, which is really nice, especially in 2020, when amount of ads on the websites is enormous.
The next idea to try is to install arm64 kernel and try to install kubernetes (or at least a kubelet).