I just bought these and tried to OTA with tuya-convert. It didn’t work. I think the device has the new firmware, outlined in this issue: https://github.com/ct-Open-Source/tuya-convert/issues/483
It is super easy to open and has nice onboard pins for serial flashing. I usually do OTA, but had to try serial flashing a MagicHome LED strip controller. Using a cheap USB UART device from Amazon and Tasmotizer it was surprisingly easy. The hardest part was soldering wires to the pads for TX/RX/3.3V/GDN. But this device has them all easily laid out. You could probably get away without soldering…just use something like sticky-tack to hold the four/five pins in place for 5 minutes. If you’re only doing two devices it might not be too much of a pain.