I am a big fan of Bike Friday (made in Oregon) and their Pakit models.
To this point, I've used it for my airline life, but with that said, I feel the points that make it a great layover bike are relevant to general aviation.
The BF Pakit is relatively light, and folds up pretty compactly. I hang the folded bike on my 22" roll-along luggage. It goes through a TSA scanner. I can put it in the 737 coat closet, or even in the overhead bin.
Best of all, it was custom ordered, and uses universal bike parts. The Brompton, on the other hand, weighed about 5lbs more, and was $500 more for a similar configuration. The Brompton also uses proprietary parts.
The Pakit is also available in a e-bike configuration.
https://www.bikefriday.com/folding-bikes/e-pakit
I currently fly a Lake Buccaneer for fun,and rear seat / cargo access is not great. This folder works for the Lake too, because I can lift it up and into the back seat without too much of an issue.
ZP