The BlueJayF4 is a cheerfully simple ST Microelectronics F4 based Flight Controller.
There was no simple F4 based board out there at the time to operate in place of the simple F1 based flight controllers. This is the FC designed for those wanting F4 performance but maintaining the F1/3 simplicity - i.e. it comes with non of the extra trimmings - it's bare bones - it's acro you might say .
Betaflight or iNav is the firmeware needed for the BlueJayF4
Support for both Quadcopters and Hexacopters
Available here until stocks run out for those wanting to directly support @blckmn.
If you are looking to mass produce and distribute BlueJayRC products, like the BlueJayF4, then wholesale options are available.