Device Type Handlers are part of the old architecture and are no longer available.
Edge Drivers are part of the new architecture, and just like the old architecture, there are both stock versions provided by smartthings and custom versions created by community members. But you add them to your account in a different way and you don’t use the IDE for them.
See the community FAQ. It should help clear up the confusion.
FAQ: I have no idea what Edge is. Is that a new developer tool? (2022)