The switches are not available in a standalone package, the current design integrates into a custom PCB. In theory there could be something that is mechanically compatible with Cherry MX but it would require quite a lot of PCB rework. These switches require power and ground as well as sense lines. It's much more like Topre than Cherry MX in this regard.
Given that, I'm not sure how meaningful the answers to the rest of your questions are, but I'll try. The switches are just about the same size as a Cherry MX switch, I don't have precise numbers handy. Since these are built around a PCB the magnet doesn't protrude at all, the entire assembly sits atop the PCB. The magnet would be centered over the PCB hole but not go through.
If I were to offer a discrete switch component - which is a long way away - I would likely design it so that the entire mechanism sits on top of the PCB, and that little through hole is where I expose the power and ground connectors. But given that all of this would require tiny custom PCBs and tooling for a new part I don't see it happening any time soon. The "unified PCB" approach for full boards is so cost effective that doing discrete switches would be a huge step backward.
Thanks for your interest, great questions!