Not sure if you are totally locked into 700c or not. Any folding bike will be a compromise, the question is does the designer compromise more on portability or on rideability. Sounds like you do not want to compromise much on rideability but it does not need to be highly portable.
Airnimal makes a couple 24 inch wheel bikes if you are mostly looking for a bike that has a ride that is similar to a normal full size wheel bike, but is quickly foldable to put in a car trunk. But I do not know if there are any USA distributors at this time or not, I bought my frame and built it up over a decade ago. Their Joey is more of a commuter while the Chameleon is more racy.
When I first started riding my Airnimal Joey, I could feel the flex in either the stem extender or the seatpost mast, or both and it bothered me a bit. But after a few hundred miles, I got quite used to it.
Photos of mine at this link:
https://www.bikeforums.net/20336169-post735.html
The second photo shows the seatpost and handlebar stem still attached to the frame, but you can lower the seatpost much further or slide it out completely. And a quick release removes the stem extender from the top of the fork to make it much smaller than shown. To fold it you remove the front wheel as shown in the photo.