Imho, the "just buy it" or "patreon to access the development discord/forum/whatever for OSS" seem like the best approaches. Like, I'm in Mastodon's patreon, and I'm happy to buy software. And while it may sting, I'm okay with "major release = new version buy it again". Not fond fond of installed local non-cloud software in the SAAS business model.
It's exactly Patreon or one of its many competitors. The "subscribe to a creator and get special perks" problem is common and solved, but as you note the "CaaS" (creator as a service) model isn't for everyone.
Imho, the "just buy it" or "patreon to access the development discord/forum/whatever for OSS" seem like the best approaches. Like, I'm in Mastodon's patreon, and I'm happy to buy software. And while it may sting, I'm okay with "major release = new version buy it again". Not fond fond of installed local non-cloud software in the SAAS business model.