I use my old Galaxy S9+ to run all my smarthome apps. There’s so many janky apps for various smarthome devices that I don’t want on my personal phone. I created an entirely seperate google account for the phone and have all the awful apps running on it. The goal is to have it also power a display with a Home Assistant dashboard. I also have it on a separate vlan so if it gets hacked/compromised they can’t access the other computers on the network.