Iirc you can give a nom de guerre and they don’t ask questions, but if you want to move past a certain rank, you have to normalize relations and any open criminal cases with your original country of citizenship (though I’m sure there are exceptions, like if you’re an Afghan national and, you know, don’t want to be executed by the Taliban).
If you mean the French Foreign Legion, they don’t forgive crimes, but they will allow you to join with minor crimes.
Iirc you can give a nom de guerre and they don’t ask questions, but if you want to move past a certain rank, you have to normalize relations and any open criminal cases with your original country of citizenship (though I’m sure there are exceptions, like if you’re an Afghan national and, you know, don’t want to be executed by the Taliban).