PostgreSQL does not have a similar object type as a package in Oracle so you need to break the package into separate procedures and functions. What comes to the naming, I don't see any specific reason to retain the name of the package as a prefix unless you have procedures (or functions) having the same name in different packages.
Few things you need to be careful with
- Privileges, in Oracle, the privileges are granted to packages so when you break the package to separate procedures you need to apply same (or similar) privileges.
- Common definitions, a package header may contain definitions that are common to all procedures inside the package. You may need to define a common procedure/function/type or another alternative is to repeat the definition in all procedures where needed.
- Non-visible procedures etc, a package may have procedures or functions that are not visible from outside the package. Again you probably need to separate these to individual procedures, just make sure they can only be called from proper places and by proper users