Dahon GB1/GB2, order from usa?
 

Dahon USA doesn't import them. Where can I order from usa?

I m not sure the GB1 and GB2 were a commercial success; i seem rather rare.

if you are handy, may be look for a cadenza which you could convert to drop bar and either keep as 2x9 with a sora mech disc (need road disc caliper) or upgrade to 2x10 tiagra or 1x10 wide range microshift advent X.

the cadenza is 26” rather than 27.5”

I'm looking for a folding gravel road bike.

Ritchey does a breakaway outback but I am not aware of folding gravel bike with large wheel hence my suggestion of building on up yourself. The Cadenza and GB1 (as I said very very rare) have very similar frames; the main differences are the handlebar and the groupset and the tyres.
you could also get a montague navigator and custom build it to gravel type
https://www.montaguebikes.com/foldin...-montague-fit/
or a change hybrid and customize it.

How would a 27.5" Cadenza suit you?
https://cimg0.ibsrv.net/gimg/bikefor...97d33b6bb2.jpg
https://cimg1.ibsrv.net/gimg/bikefor...42464d5731.jpg