It's relatively actively maintained and, from the looks of it, fully works under Windows (due to it being a full Bluetooth stack and not just a binding to the OS stack), unlike PyBluez which only supports the RFCOMM protocol under Windows.

https://github.com/google/bumble

(On a side note: If Linux is your only target, calling the BlueZ dbus interface directly with e.g. dasbus would be the ideal solution)