Board: You might try https://flashquark.com/product/gb-mitosis-wireless-split-erg... and seeing if you can get custom switches installed. I believe the pin outs are the same, so it would just be a matter of sending them switches they don't currently sell, if they agree.

For keycaps, Signature Plastics is where I buy blanks. DSA profile will be your best bet, given how strange split board layouts can be.