Many folders take very generic parts. Brompton less so.
Ori has most parts that can not be replaced by something general or a non ori replacement. Same for birdie and a bike friday is virtually a frame.
If back up concerns you then a jifo might not be the bike as as far as I can see it uses a lot of decideacated parts. Dahon spares have a mixed reputaion, so goinf for a rare bike like a jifo may not offer great support. Although I have rarely had a problem sourcing parts, I would not be confident getting jifo spares in 5 years time.
The mu uni should be supported for a long time as its a fairly generic dahon.