Hi all,
I've got a tiny 400w heater in my bathroom towel radiator. It's controlled (as a fused spur) by a dumb timer switch, which is at the back of a built-in wardrobe in the bedroom.
I've got the twin&earth coming into the metal back-box, and another twin&earth heading out to the heater.

I want to be a bit smarter, only running this if the heating hasn't been on (which I monitor from my Nest via node-red), at different times on different days, and not if I'm away.
The Sonoff T1 'touch' light switch seems cheap at a tenner and flashable.

My questions:
Is it electrically safe to use this device (or any light switch) to switch a 400w heater? (Spec says Max. Power: 600W/gang.)
Will the 'touch' light switch be activated by clothes brushing against it (remember it's a the back of a wardrobe!).
Are wifi switches OK with a metal backbox?

Any alternative devices or approaches, or other advice much appreciated.