I don't need a 60% layout with number keys but I do want arrow keys, so I've decided to go with borrowing a 40% layout from Akko that I really like. This is a picture from an online listing for the Akko ACR TOP 40%, which I've fallen in love with as far as the key layout goes, however I'm going to replace the CTRL, ALT and WIN keys with the CMD, OPT, CTRL keys for Mac. There is no caps lock on this design, and I think for a conversational keyboard it isn't needed.

Here's the beginning design for the keyboard in KiCad, which I'm learning as I do this project. Nothing is routed to the Pi Pico W yet, but you can see where I intend to put headers and have the Pi Pico W mounted to the back of the keyboard PCB.