Not OP but I have a lot of home automation. I did all of the work myself. It’s easy enough to swap the wall switches and the thermostat back to what came with the house.

A lot of my stuff is set and forget. Home Assistant doesn’t need to be updated or monitored. As long as nothing talks to the internet, all I need is backups of the config and spare SD cards.

Maintainability is a concern that I haven’t figured out yet :) Right now my plan is to replace my DIY thermostat with off the shelf device suitable for my boiler when we sell the house. All the advanced features will be lost, but this still is the average expected level of automation in the area :)