Hi yorgas,
Yes, we can use HL on mangOH board.
And already several discussion on this forum, i.e.
About application processor, you are correct HL does not support it.
But as you are using MangOH green, maybe you can make use the ATmega on MangOH green.
Set CN307 pin 6 to ON position to bridge HL UART1 and Atmega so you can run your application inside Atmega and to control HL.
Please refer to developer guide for details.
Hope it helps.