where/how do i get started
I guess you could add support for adafruit arcada and then it would be compatible with other f4 boards
i think there is documentation on this on the makecode website
but i personally recommend using a raspberry pi 0
You can make arcade hardware but I never try it before.
On the hardware page there is a section at the bottom about developing a new board with support for MakeCode Arcade. In particular, it links to “Creating your own Arcade hardware” which will be helpful. There is a list of supported microcontroller families and other hardware, or if you want to use different hardware, there are more resources here.
It also lists other boards developed by other companies that you can take inspiration from. (Most of those companies have released their design files which helps!)
There is also another section about wiring up joysticks and buttons to a Raspberry Pi, if that suites you.
There is a page in the online documentation for MakeCode Arcade that speaks specifically about creating compatible hardware.