The only thing I could think to build on blockchain is electric utility metering / settlements data, but I fear I'd be laughed out of the room at this point
I was lazy that day. But today!
I just used procmon, filtered to include "systemsettings.exe", turned off all the other guff and just saw network packet meta data (no content).
And yes, as you browse around system settings there are TCP connections to MS servers. I don't know that they are "blocking" though and have run out of care factor.
I'm working out how I can make a vst type bridge to stream audio in and out of other DAWs, I'd love to use it in realtime with Live. I've had a lot of requests to put the binaural processing into a vst too, which I'll consider later down the line!