[Tyrannosaurs]

Technically yes but:

1) This is really an option for a relatively small part of Android's install base most of whom don't know F-Droid exists, let alone how to install it or why they might want to.

2) Any company wanting to produce a phone on this basis is (a) depending on a lot of other products and organisations and (b) putting out a product with - for instance - a substandard maps product next to the competition.

So yes it's open, but not in the way that I think many would like it to be (that is where a genuinely open phone that the average punter can and does use exists).