There is already a total count of up- and downvotes, but please never add karma to Lemmy. We don’t want to deal with karma farmers and minimal karma requirements to post. I don’t care about the moderation issues because karma brought more harm than good. Please never add that bloody dreadful thing to Lemmy. I already saw a bunch of people supporting adding karma to Lemmy, which will turn Lemmy into a cheap Reddit clone and karma-farming hell. Please, never add karma to Lemmy. I beg you. No more karma hell.
Karma aka. Reputation is already a thing. It’s not all that accurate because up-/downvotes from/in defederated instances aren’t counted, but the information is out there for anyone who wants to know. See my 1st level reply to OP.