One thing I really dislike about the Mobile ecosystem is how much different each device is to each other.

I thought you were sarcastic when I first read this part, since way back when phones used to be innovative in both hardware and software. The current market offerings are all carbon copies of eachother with a strong trend towards converging into the exact same lineup.

Multiple cameras, one in front, 2+ in back. A power button and two for volume. Reader apps may hijack it for scroll. Gesture movements. Fingerprint and face id. Less and less conusmer freedom in software choice. Irremovable battery. No removable back plate. A rectangular brick. A near-100% display area. No headphone jack or SD card, with SIM on the way out.

Covers the vast majority of offerings on the market, with a few slight adds/subtracts. Dumbphones are a rounding error.

This definition covers even tablets, and it isn't even deliverately vague.

Without much experimentation and development on the hardware front, no wonder software's behaving exactly the same.

There just isn't enough interest for proper innovation and experimentation.