[AD] What if your keyboard could change shape?
(Note that this is not specifically an IC, as this will be available to purchase from stock when finished, but I'm trying to gauge interest.)
Imagine that one minute your keyboard looked like this:

And just couple of minutes later, it could look like this:

Or with a little more time, and a firmware swap it could look like this:

Or this:

Or:

Or if you prefer this:

All with the 'same' hardware, you need one or two docks, and however many sets of matrices. The Dock is the 'brains' of the operation and each contains an RP2040, two USB C (one for the link), and to start with an OLED and encoder.
Edit to clarify: The dock contains the MCU and is wired to start with. Other dock parts can and will be added to the system, and could for instance hold a touchpad instead. The main intent for now is wired only, but there is no reason it couldn't expand to BT or a dedicated 2.4Ghz link to a dongle in the future.
All configurations by default is designed with a sandwich case, with also secures the parts together using a set of thumb screws. Parts are 'hot-swappable' in so much as with some planning, the software can support going from split to uni-body with the same firmware, which is the main usage.
In practice, it could probably even swap from an ergo layout too an ortho layout, as long as the keys/matrix match. (But more than likely you will *want* to at the very least remap it in VIA or Vial in this case).
In practice, you could design whatever hands you like, as long as they have a flat (inner) edge, with space for the 20 pins of the dock. Each hand supports 1-2 encoders, and up to a 7x7 matrix with full per-key RGB, in addition to what sits on the dock. (Once tested, the measurements needed will be made public)
The hands can in theory also support an OLED on the matrix, but that would cause conflicts when docked, so it's limited to one in total for the docked keyboard, either on the dock or on a matrix part. Same would apply for things like a touchpad, which I think would be entirely redundant to have more than one.
So, the big question is, how would you like your keyboard to look like?