many people still considered windows a monopoly, when you could easily buy redhat at most local stores. MS Office file formats were also considered a monopoly by Richard Stallman, because businesses used them and it was difficult to now change (there are tons of competing formats).

the tech industry likes to change definitions to fit their viewpoints.

What people think is a monopoly and the legal definition of a monopoly is different. You have to be able to show harm to e consumer, something's hat is going to be challenging to show with a handful of hidden APIs. APIs, it should be noted, that somebody could implement themselves (at least for the sample given; whether it would be approved is, of course, questionable).

On the other hand, it could be used as evidence of part of a larger anti-trust case, but given that Android devices are cheaper, perform just as well, and have a strong ecosystem, that's going to be hard to pull off.