The main thing that makes all this hard to do is the form factor.

Give these phone batteries a standard geometry and interface and pretty much all these problems immediately go away. 3 prongs on the battery (ground, positive, data). A standard protocol so the battery can communicate things like SOC or acceptable charge rate with the charger. And viola, you are off to the races.

Yes, this will mean manufacturers will have a hard limit on how thin they can make their phones and a constraint on what designs they can employ.