what I would do:

upon defeating the final boss (how ever many that will end up being) Odin presents himself and gives you two choices.
1. you can choose to remain in Valheim and maintain Odin's peace. If you do, he presents you with the magic "cheat sword" that you can spawn in with commands. the thing absolutely WRECKS and it's super fun to use.
2. you ascend to Valhalla. if you do, it perma retires that character, but the next new character you make has some kind of "blessing" from the retired one; a static boost, perhaps start out with +5 to all skills, or something similar. maybe choose from a list.