Victor_Weismann
Do they still have the genesis chamber? If they do RAO can really hasten the process of repopulating krypton. Also i am pretty sure that very few beings would want to mess with them,besides the very advanced tec they have thousands of kryptonians under a yellow son, just clark was already powerful enough to defeat a monster like darkside and he wasn't even a soldier,now imagine what thousands of them could do.
you can use genetic manipulation to improve or get new powers or you can use asgarian system power of getting divinities and be God of the sun or w.e you think is best for your story. if you really want to have a pure kryptonian MC then the second option is great plus with an unlimited ways of improving the overall flow of the story.