I'm not asking if you're an Android dev to disparage you, I'm asking because the two features are outwardly very similar, but have internal differences. And you can use one to get a result that looks similar, but is not the same, as the other.
> I'm asking because the two features are outwardly very similar, but have internal differences.
Prove it, then. What are these "internal differences"?
Let me reiterate: there is literally nothing that relies on a proprietary or private API in the former Chrome merged apps and tabs implementation. Any app can do the same thing using completely public API's.
I've already linked the API's required to do this. I've linked a third party app that provides the exact same functionality. Which part is unclear to you?
Yes, it does. Which part do you not understand?
> Supporting being a provider for Custom Tabs has nothing to do with being able to have your tabs show up in Recents.
No, but if Firefox supported Custom Tabs, you could use it with Chromer.