if you’ve already got something running 24/7, you could just put it there. it doesn’t need much for resources.

pihole does not need it’s own box. it can run as a container (docker instructions in the official docs) or in a small vm.

i have two small vm running dietpi and used that to install pihole. i fully expected to run a few more things on them, that’s why i chose dietpi–just have never gotten that far (it’s only been like three years now).