What's the process for porting to a new Arduino boad?

[znmeb]

I have two Arduino-compatible boards that I want to port eForth to - a Teensy 4.1 and an Electo-Smith Daisy. Both work with the Arduino IDE They're both Arm Cortex with the floating point hardware. I don't need assemblers initially but I assume I can develop them if I do - I'm pretty familiar with the GNU assembler for the RP2040.