The magic of the existing hourglass model, and the entire premise of the end-to-end principle [1], is that you can build all those features on top of the infrastructure provided by IP. IP as the skinny neck allows service providers to focus on delivering one thing very well, and enables anyone who wants to use that infrastructure to build anything they can think of on top of it.
This is not entirely true with PON (passive optical networks). The ONT is more than a media converter (optical -> copper), it facilitates the conversation with the OLT (Optical Line Terminal) further upstream. That connection is not an ethernet connection and needs specialized hardware that can communicate using the PON protocols.
The ONT is managed by the service provider and provisioned with their tooling. It typically holds the user profile of the customer, and contains information about the subscribers service level. It is not something that can reasonably be replaced by the end user with their own hardware.