Pacific Cycles uses the Zehus integrated hub that is also used in the Vellobike+.

All assisted folders face the weight increase problem, anybody willing an assisted folder must accept some weight increase.

I think it would be possible to integrate the Fazua crank motor in the Birdy frame. The Fazua solution weight only about 3.3kg in total (including a 252Wh battery).

The problem is that Fazua is an high end expensive solution meant for high end road bikes and the R&M Birdy is already pretty expensive, the Fazua assisted Birdy would probably become much too expensive ?