As an example of how this can be done well, I believe nostr:npub1yx6pjypd4r7qh2gysjhvjd9l2km6hnm4amdnjyjw3467fy05rf0qfp7kza set up a system for "reserving" bounties related to Corny Chats. So devs can apply, get locked in, and get paid upon completion. Those bounties were also clearly defined and dealt with bite-sized bits of functionality (like adding support for a certain NIP to the Corny Chats app). That's a pretty good way of soliciting open-source contributions.