Typically GPON is deployed with a standard copper Ethernet presentation. So there is nothing Meraki need to do.
How is it being deployed in your country that prevents it working with Meraki?
GPON fiber solutions is typically just a layer 2 transport so though the gear may not be Meraki, I don't see why you couldn't have a Meraki switch connected to a GPON ONT through your fiber cabling to a GPON OLT where it uplinks to a Meraki core/MX Appliance. Network topology view would still show non-Meraki components as long as it supports CDP/LLDP. Maybe I am wrong, my wife says I am all the time.
i was planning to use it for a small FTTH project with 200 users.
I know there are others vendors, but i just think it would be nice to have meraki end to end.
And also have a enabled API network gear...