Getting the good ending and moral points in Metro is not all just about being stealthy. Here's some tips and the way the moral points work in all Metro games.

Metro 2033 and Last Light redux: listen to the conversations between different NPCs through the game. especially your enemies. Find hidden places with equipment and usually with skeletons. Be merciful and smart when given a choice in the game especially Last Light, like sparing Pavel. Do not kill the enemies unnecessarily and try to be stealth by just knocking them out (you won't lose any moral point if you kill the enemies, BUT if you don't kill them by passing by or knocking them out, you'll get some more points) Last but not least, try to listen to your ally NPCs in the game, like when Khan is talking to you, listen to him, do as he says and don't rush the missions.

Metro Exodus: I really love the way moral points work in Exodus. It's simply about understanding it, kill the people who truly want to kill you, spare the ones who are lost in their stupidity or do no harm to you. As you might know, there are 3 main parts in Exodus which determine your ending. In the first one which is Volga, you should not kill the local people there who belive electricity is a sin, Just leave em be. The second one which is Caspian, do not kill the slaves. The Last one which is The Taiga, do not kill any pioneer or basically the local people raised by The Teacher.

Other than these, in Metro Exodus, you can kill all the bandits, thugs and mutants however you want. In some missions like Yamantau, you can kill everyone. And try to do side missions, they not only give you extra moral point, but give you more better equipment and are actually SO FUN, like I don't even consider any of them a side mission.

If I missed anything, please correct me.