GNOME Foundation partners with Purism to support its efforts to build the Librem 5 smartphone

I wouldn't say that nobody cares. Obviously a lot of existing users care. If they don't care then they should. Having a open source as possible phone is extremely valuable in it's own right.

I really don't think the OS matters that much to the phone really. It's just a hardware platform. It's the hardware that matters. It's going to run Android if it runs anything. So it will quite happily meet the needs of most any smartphone users. Everything else will be a bonus. It will have the added benefit of having the ability for people to hack around on their own thing and work on sailfish or whatever else they feel like.