Thanks for nw.js, I’d never heard of it before :)

I think it is supported in Windows but 8.1 and later as per https://github.com/WebBluetoothCG/web-bluetooth/blob/master/implementation-status.md

That said I tried it on a Windows 10 box with 2 different Bluetooth 4 dongles and it doesn’t see the meter where as my MacBook Pro right next to it does :-/

I also tried it on someone’s laptop running Linux and it was found by Chrome and we could connect but it didn’t complete and I wasn’t able to work out the details.