Any reason why this won't connect to an Apple Watch?

[edwardrossi]

As far as I know, Bluetooth keyboard's are compatible with Apple Watch, yet I cannot connect the T-keyboard. It doesn't even appear in the Bluetooth devices when in pairing mode.

It's a Series 5 running WatchOS 10.2.

On a side note, it appears and connect flawlessly to iPhone.

For context, I bought the T-Board to connect to my Apple Watch to see how it performs as a dumbphone.
If it passes proof of concept, I will play with some designs and 3D print a case integrating the Apple Watch body and the T-board into a single integrated device.

Any ideas?