I believe we've started work on the Raspberry Pi 4 but I don't know how far that has progressed. And I don't know if we had plans for the Atmel device.
It can take weeks to add a new family of devices to Flowcode, but if the new devices are very similar to existing devices (in terms of programming tools and toolchain compatibility) then it can be a lot quicker.
We don't offer any training or information on allowing you to do this yourself. The FCDX files contain most of the information required to support a new device.
As far as I kow the Raspberry Pi 4 works just fine, just use a Raspberry Pi 3 definition file, the two boards are the same in terms of pin out etc so this should be fine.
As for the Atmel SAMA5D3 there are currently no plans for this.