I build a new set of wheels using an XDR compatible rear hub, a Hope RS4 135mm OLD 5mm quick release.

The rear wheel of the Birdy disc is standard 135mm OLD 5mm quick release.

I also build new front wheels because I changed the wheel size, I have now two sets of wheels with XDR hub, one in ETRTO349 (Brompton wheel size) and one in ETRTO406 20" wheel size.

The front wheel hub for a Birdy disc is a little bit more difficult because even if the 100mm OLD is standard, the disc mounting on the right side and closer to the center of the wheel than on a standard disc brake front wheel, so a specific Birdy disc front hub is needed.

Some rear hub have an exchangeable freewheel (its the case of the Hope) but none of the rear hubs mounted on the Birdy have that (excepted the Pacific Cycles 11SP Birdy with Hubsmith wheels).