Ok, now that I see a photo. I don't know if there are any vendors that have single junction box switches that control three lights. In general though, the smart

Ok, now that I see a photo. I don't know if there are any vendors that have single junction box switches that control three lights. In general though, the smart switches tend to be deep and don't leave a lot of room in the junction box. Are you sure you don't have a neutral wire in the junction box? In my junction boxes, the neutral wires weren't used for the old school switches but are capped in the back of the junction box. Regarding the interface, the Wemos are not very reliable because they are wifi. I used to use X10 and they were way more robust than the Wemos. You might want to check X10 if you're going to code yourself. The hardware tends to be a lot cheaper than the newer switches.