Not GP, but a listing of groups using PostgREST in production can be found here:...

		thelambentonion on June 24, 2017 \| parent \| context \| favorite \| on: pREST – A fully RESTful API from any existing Post... Not GP, but a listing of groups using PostgREST in production can be found here: https://postgrest.com/en/v4.1/intro.html#in-production