Jipe

It depends for what.

For the front block adapter, there is a version for Birdy 2 but not for Birdy 1 I think ?

For the wheel size swap, its only possible with disc brakes. Only part of the Birdy 2 have disc brakes, no disc brakes on the Birdy 1.

For the folded size, the Birdy 3 is slightly smaller than the previous one and the previous ones had some problem of chain derailling when unfolding that were solved with the new chain tensionner that appeared on the Birdy 3.

For the off road use, the rear swing arm of the Birdy 2 was less strong than the one of the Birdy 3.

50mm wide tires ans suspension exists on all Birdy since Birdy 1. There are front low rider and rear racks for all Birdy since Birdy 1
.
For the efficiency, Birdy with Shimano IGH should be avoided, these IGH are less efficient and their gear inch range is too limited.

The efficiency of the SRAM dual drive and the equivalent Sturmey Archer hub is also lower, so Birdy with SRAM dual drive ans SA hub should be avoided too.

So, remain Birdy with a derailleur system (there were several model names for it, its currently called Birdy Touring by Riese & Müller, but previous Birdy Touring had a SRAM dual drive and current Pacific Cycle Birdy Touring has a SA hub) and the Birdy Rohloff.