Do you think there will be a good custom with Bluetooth?
Given that metal doesn't work well with connections. I'm looking at a Zoom ee V2 or waiting for a 65% with Bluetooth. Missed the GB for a recent one I think.
If you get the type of board where you add in your own microcontroller, you could replace a pro micro with a nice!nano. I don't know how common that is on non-split keyboards, though.