Fun fact: while not being exactly like what karma was on Reddit, Lemmy does store the total count of upvotes-downvotes your account has received. You probably can’t see it because it isn’t shown by the frontend (the website you see), but the data is indeed there.
I never considered doing that, actually. I always felt like PRs where only useful when you actually had something to show, otherwise you are just spamming a project with useless ideas and "what if"s.
But this is also my first time contributing to an open source project. Learning experience.