I'm not sure what you mean by another mode. Something like a different story/campaign? Maybe will have that one day with an DLC or Underrail 2, or even better a tool where we create our own modules and import previous characters.
Anyway when you export a character it will be stored in a folder called "Character". When you start a new game, at the bottom of the screen where you distrubute your stats, skills and feats there is an "import" button where you can chose any of the previously exported characters and start a new game with it. They will have the exact stats, skills, perks and all inventory equipment but everything in the world, including the stored items at the home, quests etc will be back to default state.
Yes, an endgame character will be crazy overpowered for the most part of the game. There is still a level 25 cap so as you progress towards the endgame again the difficulty will naturally normalize over time.
