This may not be the right place to make this argument, and I fully understand your plans may be firm and I am wasting my time by saying this. However, I would argue you almost certainly have a captive base of enthusiasts beta-testing your product rather than a high percentage of normies. (I apologize for that term; I can't think of a better word and don't mean it as an insult to anyone.) Given that assumption, it would seem that the phases are almost backward in an ideal world. Enthusiasts are likely going to go the extra distance to get what they want running on their NAS whether they have a HexOS way of doing it, or if they have to do it from TrueNAS. It would make more sense to have the custom docker/deployment script loader available first, with a suitable warning of dragons and dangers ahead, and provide an open-source example of a curated script so the community can start making and sharing custom app deployment scripts the HexOS way. Maybe have a forum section for sharing and collaborating/improving the scripts. Then you would already have a portfolio of proven community developers once you are ready to recruit, and (if you so choose) you can give out a "HexOS stamp of approval" to well-designed community app deployments. Finally, for the popular yet difficult apps that require a demanding configuration/deployment, work on curating them yourself later. I understand that you might need to make a few curated apps to define the "HexOS" way of app deployment and to develop a best practices guide for the community before allowing custom deployments, but by just opening the door, I suspect you will have a very nice catalog before you know it. Furthermore, I suspect the community will naturally develop deployments for popular apps you may already be internally planning on curating, therefore, saving time and money from having to develop them yourself. This would ultimately allow more development budget for critical features/integrations.
To be clear, if HexOS were in wide release, I would completely agree with your planned phases. However, because this is still a beta, I think it would be advantageous for HexOS to foster community development sooner rather than later.