The open source scene is completely dead in the water and so is fine tuning for individuals.
Why do you think that? The existing data sets won’t be going anywhere. Fine tuning doesn’t require nearly the same amount of training images and it’s not infeasible to get them from individual artists.
Not that that actually matters to open source developers, though, as the developer obligations only apply if you’re making the product available for a commercial purpose, so they’re not relevant to developers of gratis solutions - and most libre developers are also gratis developers. If your platform is not commercial and doesn’t have at least 25 Million monthly active users, you don’t need to allow users to add content provenance information in the first place. If it’s not for a commercial purpose, you aren’t prohibited from training on content containing content provenance information, or from removing it and training on it.