I doubt it'll work out.

Other than highly mechanical tasks, the time investment to resolve an issue is unpredictable. It's highly unlikely someone only interested in monetary compensation would just randomly pick up an issue in a random repo and work on it. There's a reason why most contractors bill by the hour rather than by number of JIRA tickets closed.

Even if there are people interested in the bounty, it'll eventually turn into the 99designs of coding: dozens of people competing to be the first to resolve an issue and that usually results in a drop in quality for speed (see Goodharts law)