Controversial hot take:

Simplify the orthography to make it phonic, and then people spell words however they are pronounced in their local dialect.

Much of the variation between accents lies in the unstressed vowels. We could simply omit those, treating the alphabet more as a semi-abugida.

You'd end up with something pretty close to early 2000s txtspk, so it might actually be a surprisingly easy conversion for many people.