Here https://dbconvert.com/mysql/postgresql/ you can find good information.
As written "Transferring data between two different management systems is not a trivial task. "
Laravel use mainly "common functionnalities" between both DBMS, so the best way to try first, is to save your project, change (in .env) the DB type et remigrate everything, it should work if you don't use MySql specific (personnaly I always use Postgresl)