RPi5 is definitely a huge overkill. Plus, it needs a power adapter, probably some cooling, and some space to seat it. Pi Zero 2W + micro usb ethernet adapter w

RPi5 is definitely a huge overkill. Plus, it needs a power adapter, probably some cooling, and some space to seat it. Pi Zero 2W + micro usb ethernet adapter works perfect for Pi-Hole, and has an almost invisible physical footprint: Small enough to hot-glue on the back of your router, happily runs with power from one of the router's USB ports, and you get a 10cm ethernet cable to avoid network cable management.