Question asker posts a bounty. Some algorithm decides which answer(s) receives the bounty. But that seems really hard, which is why I'm moving on to a different idea.

My new idea revolves around making it so only a targeted influencer (e.g. twitter handle) can answer and claim the bounty. The bounty can be increased by the question asker or other people.

When I say custodial yes I mean deposit ahead of time, like what stacker or vida.page has.