In the UK at least, the lighting circuit contains a neutral wire, so this shouldn't be an issue.

It does here also in newer homes. But just getting it into the switch and then shoving everything back in the box is a challenge. Smart switches are much fatter than normal switches, and by boxes at least were wired with hard copper that was difficult to shape. I had to take out the switch for my cabinets to make everything work.

Even a controller for a ceiling fan is a challenge. Sometimes, if you are lucky/persistent you can replace the box itself with a deeper one to make wiring easier.

I want to get a deeper box in eventually, but I have the feeling I should hire an electrician to do that, then the dry wall will have to be redone, and...maybe it isn't worth it now. Besides, I can get some good battery operated cabinet lighting to replace the ones I sacrificed the switch on.