From https://stackoverflow.com/a/79604825/3872647
The Omron device transmits BLE but to read data, it requires pairing.
Are there any HA examples to perform pairing and extract data from BLE devices that behave like this?
Be aware the Omron only gives out the data once, and if the official app snaffles it, it isn’t there for your perusal.
The protocol is not well documented and you may need to do some extensive snooping to work out the encryption.
I would welcome an integration that would be able to spring into life when I put on the sleeve and press the go button.
BLE sniffers such as nRF Connect may give you clues for characteristics to code for.
The official app will definitely be banished if I get it to work 
I am looking into the same topic, but with my very limited skills won’t be able to program anything on my own. Happy to test, though
What device do you have?