I’ve no idea what GFCI is.
Okay. I’d assumed there would be no need of any mechanical timer since you are replacing it with ‘smarts’
Me neither. Sounds like that narrows the field considerably.
Most folk just pop everything in a weatherproof box. But see -
As discussed already, many mains powered types would need a small modification to isolate relay terminals. Some are isolated out of the box.
Maybe we’re at cross purposes here. In a typical openHAB system these functions are performed at the central host; the ‘smart switch’ here is really just a remote control relay under centralized smart control.
This is an openHAB forum so that’s naturally at the heart of the suggestions you’re getting.
If you’re wanting something monolithic you might get more joy in a landscapers or serious gardener’s forum?