Joe W3JDR is working on a Raduino Pill board which is a direct replacement for the stock Raduino, but with an STM32F103 processor and much more I/O. I think it hits all the points on your wish list. I released the PCB to fab a few weeks ago and am waiting for boards to arrive from China. Assuming it functions without major rework, I’ll post the CAD files and Gerbers on my web site and encourage others to develop for it. I plan to immediately mod the stock uBITX firmware to run on it, then will expand functionality to incorporate the work I’ve done with TFT displays, hi-res encoder and software S-meter & AGC. I’ve cleared my bench in anticipation of arrival and am checking the mailbox every day.