So what is my best bet ? After posting this thread, I found https://help.ubnt.com/hc/en-us/articles/205202560-EdgeMAX-Add-other-Debian-packages-to-EdgeOS .
Should I simply compile Griggi for debian, copy the .deb file on Edge-Pro & then do an install ?
Also - Griggi integrate with DHCP server (dnsmasq on Openwrt) as the DHCP server to need to signal Griggi when a new device comes onboard. I guess EdgeOS also uses dnsmasq. Should I recompile dnsmasq for debian with Griggi signalling & put that on EdgeOS too ?
About source thing - we have not (yet) released the source for Griggi. Frankly, the whole thing is being created in a very ad-hoc manner (we guys are not embedded/kernel devs & have to hack a lot of stuff which is pretty ugly), so I am not sure we would ever release it out. Is that a problem when it comes to porting our stuff to EdgeOS ?