For those who are interested in the STM32 Onstep controller, or were considering it but were concerned about its speed, there is a new microcontroller to replace the STM32 bluepill, called a the Robotdyn STM32F303 and it's apparently 2x faster. It's also plug n play if you want to upgrade your existing build.
Khalid Baheyeldin just released this youtube clip explaining it in more detail and it's now on the Onstep group wiki.
https://www.youtube.com/watch?v=wQCT6ukKtL0&t=447s
Cost of the new driver on aliexpress is about $15 delivered compared to about $6 for the blue pill and there are no issues with having to short pins or solder on additional resistors. Link is below.
https://www.aliexpress.com/item/3301...501e4c4de6Yuk2