Oracle Migration Approach (Open source vs Vendor Specific)

In our company we are looking to migrate oracle db to postgres , now since we dont have any expertise in Postgres in our organization so we are planning to go 

with AWS aurora or EDB postgres so that we have helping hand in migration(in dev and dba) while we get mature in postgres ... do you guys think after 1-2 years if required it will be easy to move from EDB or Aurora to Open source Postgres assuming we dont use AWS services OR would you suggest to move to Community version from the start by taking support/consultancy from other companies like 2nd quadrant and etc?

All our developers are experienced in pl/sql so I assume it will be easier to learn PL/pgsql  ,isnt that right? so far only things i dont like about PL/pgsql that validation of program units doesnt happen until you run it ... though i did find extension plpgsql_check to achieve that to some extent.

Regards,

Sandeep