While I wait for Flex's Developer Program manager to make contact with the details, I confess that I'm very curious as to what Flex Radio have planned for developers.
A developer program can have a lot of moving parts, but maybe not all from the get go.
To begin with there's the simple issue of access to the APIs, or if any tools are required to the SDK.
In due course, APIs need documenting. I gather that's not fully done yet, which is fine for me and probably a lot of seasoned developers - so long as there are ways to at least get summaries or infer functionality from samples, sources or notes.
Often vendors will want to express certain limitations, frequently commercial, as to what a developer can actually build and what they are permitted to do once they would like to ofter a derived product to others. This is where there may be distinctions between for-free and for-profit offerings and in the latter case whether there are royalties/fees due to the platform vendor.
What I'm hoping for minimally is free access to the APIs and at least the ability to distribute free apps/extensions depending on the API functionality. This seems fully in keeping with the spirit of Amateur Radio, experimentation and the encouragement of an active developer community in what is otherwise quite a niche.
I do also hope that Flex will allow developers to charge if they want to. That could encourage people to invest even more time and energy into projects that could help to fill out the 6x00 ecosystem and amplify the value proposition of the radio. To begin with though the market isn't exactly going to be large, and it may never be in any real sense. So, I doubt there's any real money to be made here, only the advantage to Flex of being seen to have a community of developers and add-on products around it.
A much less preferable option would be for Flex to want to charge extra for their API, probably via a paid developer subscription. That's a shame because it's counter-culture for hams IMHO, but also just because it's a barrier to entry. I doubt there's a very practical model for doing this anyway, both because of the logistics, but also because I can't think what an appropriate price would be (both meaningful to Flex but also low enough to work in a tiny community).
With APIs come the very real possibility of deeper tech support. This isn't going to be an issue when you have a handful of dedicated well-chosen early access developers. Both the number and type of queries will initially be limited and if the API is still early, then direct contact with the API developers is actually a good thing. As the developer community grows however, you can quickly move into another regime where this direct support becomes impossible. At this point you can try to automate 1st line technical support with tools like wikis and forums, but at some point a paid scheme becomes necessary, if only to act as a bit of a limiter on the demand, but also a way to help pay for the overheads. Again, I hope that this can start off very light-weight and free. Better to prequalify developers and then offer free online informations and occasional direct support, than to require payment for any access.
Anyway, I'm raring to get going with learning and experimentation if there are no impediments. So hopefully I'll find out how I can get started very soon.