I don't want a used laptop. I have my NUC mounted inside a small enclosure on a bracket, with PoE for power. It's a single-purpose device, only used for HomeAssistant and nothing else. It also has to be located centrally in my house for better ZigBee/ZWave networking.

Unfortunately, it's close to dying. The heat from the CPU disintegrated the plastic of the SATA cable header on the motherboard. I fixed it for now with a bit of glue, but it's not going to hold indefinitely. And NUCs were pretty pricey.

RPi with a SATA/M.2 disk and a PoE hat is not that much cheaper than Intel, but it uses much less power. They also tend to not have cables that are kept under mechanical strain. I have a single-purpose RPi that's been running since 2014, and it's doing just fine.