Gumshoe

One thing I noticed is some of the case are labeled row x column and some column x row. I believe the standard is row x column, so the cornes, for example, should be 3x6.

right hand pain.

Any sense for what is different between your hands? You sure this isn't a mouse issue?

What kind of motions cause the pain?

There are 3 basic types of wrist motions rotating along each axis. Potentially you're either doing a lot of motion in one of these categories or your normal resting position isn't neutral in one of these categories. Maybe try to figure out which of these motions/positions is causing you issues and come up with ways to try to cut back on that motion or position the keyboard more neutrally in that axis.

Also, you should look into doing exercises to help with your issue.

No, you can setup a dongle with bluetooth. In a regular zmk setup with nice!nanos or whatever bluetooth MCU, the two halves communicate wirelessly over bluetooth, a central one that does all the calculating of what key presses to actually send, and a peripheral that just sends raw keystrokes to the central one. But with a dongle setup, you'd get a 3rd MCU that you plug into the computer that acts as a central board without any keys that has 2 peripheral boards it communicates with. Because you'll keep that 3rd MCU plugged into the computer, it won't need its own battery or even any components, it can just be a bare MCU. You could also make a case for it if you wanted:

https://www.youtube.com/watch?v=YwsutNf1WRA&t=721s

Or get a 3rd MCU to use as a dongle so that acts as the more power hungry central board. Even with tiny 110mAh batteries, that'll give you 3 months of battery life with a pair of nice!nano2s.

You're kinda all over the board on which keyboards you're looking at, 36 to 80 key keyboards, some with keywells, some without, some by big companies, some open source made by solo vendors. If you're looking for just a list of keyboards to browse through, you can checkout the wiki here and focus on vendors in your region: https://gitlab.com/ergomechkeyboards/wiki/-/wikis/useful-resources. If you're looking for recommendations, you'll probably need to give us more than just something to travel with.

I would say that keywells don't make for very travel friendly boards. If you want a big company build (OEM), I think the ZSA lineup (ergodox, moonlander, voyager) are going to be the best travel boards. If you're looking at open source boards (corne, skeletyl, etc - DIY boards, they're called, but you can find solo vendors to do the complete build for you), then pretty much any flat board you find will be better to travel with than a skeletyl or glove80, and from there you can choose as many or as few keys as you want. For either DIY or OEM boards, I would just browse the list of vendors in the wiki link I posted above.

My thought was if this would be able to be controlled on a regular MX switch and if such a program already exists?

No. Most MX switches feature a mechanical switch that moves actual metal pieces to complete a physical circuit by coming into contact with each other at the actuation point. It has neither the ability to detect where in the keystroke it is nor alter the point at which the metal pieces make contact.

I say "most" because there is a thing called an "optical switch" which can have this type of capability, and they DO make this in an MX form factor, but you can't just use these in any MX compatable board, it would need to be a board designed to work with optical MX switches.

How much of this was soldered by you vs the pcb manufacture? Boards without a separate MCU have always fascinated me, but I haven't been able to price one out because haven't been able to figure out how to use JLBPCP's pcb assembly service.

I think this is the most keys I've seen crammed into such a low-pin controller. Did you have to do anything special to get the whole matrix in there?

Functional as in it technically works or that its comfortable and realistic to use?

Mx spacing is 19.05mmx19.05mm. Choc spacing is typically 18mmx17mm. And this is 16.5mmx16.5mm? Maybe its just your hands but those appear even smaller than that.