I will think about it and decide again what to get.
One other issue with the Uno WiFi Rev 2 is the possible need for firmware updates to the WiFi NINA portion of the board.
I do not know how often this needs to be done, and how easily it runs.
I can see postings on this board where it goes well and others where people have issues.
I have tried searching online to see if anyone has done the Bluetooth communication before between Nano BLE sense and Uno Wifi Rev2, but sadly I didn't find any example yet
BLE is probably less used than WiFi on the Uno WiFi Rev2 and more of the tutorials will be for wifi. Choosing this board for BLE application because of the I/O or form factor is not typical.
The BLE library used is the same one as with the Nano33 and the other Arduino BLE boards. If the wearable unit is going to be the peripheral/server, then the Uno WiFi Rev 2 will be the central/client and all the BLE examples for two devices connected to each other should be applicable to your situation.