The Glove80 is keywell-shaped, and is a product. https://bastardkb.com/ has fine Manuform-thumb-cluster keyboards.
I have printed a Dactyl Manuform; its thumb cluster has six keys, but is quite different from the Kinesis, I'm afraid. I think the original Dactyl was an attempt at making a more portable Kinesis Advantage. I guess you can maybe generate a Dactyl design at https://ryanis.cool/dactyl/ ?
I'm afraid my advice is a few years old because I haven't kept up. The Dactyl Manuform was supposed to be a stopgap, but it's worked well enough that my focus has drifted to other projects.
See also kbd.news if you haven't before. I used to think, why is this dude making his own website when everybody's already on r/mk? ... And then Reddit sold out.
Yeah, a flat keyboard will generally beat a keywell keyboard for portability, I suppose. For my current Dactyl Manuform, I printed a hard case that covers each half, and then I set them together bottom-to-bottom and put the whole thing in a bag that happens to be just tight enough. When I put that in my backpack, it's like a large plastic stone. Not flat. Works well enough for me though.