So you are migrating from Sqlite to Postgres because you need it. What is the state of your product when you need to do this migration? Is your product non trivial? Are you now dependent on particular performance characteristics of Sqlite? Do you now need to keep your service running 24/7? Accounting for all of that takes way more than 5 minutes. The only way to beat that is if you still have a toy product and you can just export the database and import it and pray that it all works as a migration strategy.