I have been thinking about this topic, and I agree that this change was a bit abrupt, with only a few days to adjust the rollout of new services via custom GPTs. This is valuable feedback.
Have you seen the announcement about ChatGPT Sites with WebMCP support?
It is a different process for creating and maintaining a service for a limited number of users with custom resources and actions, but it does check all the boxes if the user is accessing it through the ChatGPT desktop app.
What’s your opinion on this solution as the path forward?