You might also checkout Xiaomi Aqara dual-relay. It's Zigbee and there's a community driver that works with it. Not officially compatible, but I have two of them and I've never had any trouble with them staying connected directly to Hubitat (unlike many of the Xiaomi battery powered devices that are problematic on the hub). I've seen the inside of the Xiaomi and it's built well and uses good components. My experience with the Sonoff is they use very cheap components and some of their manufacturing quality is questionable in my opinion.
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