I would recommend this product from Shelly https://www.shelly.com/en-us/products/shop/shelly-h-and-t-gen3-1

Doesn't no app or hub requried, works via wifi or bluetooth, has an e-ink display to conserve battery. I've had it since October and its been running without issue. Uses 4 AA batteries which I haven't changed at all and are still above 75%!

There's a newer generation (I have the previous one) so I can only imagine its even better.