So I live in Michigan ..snow/ice 4 to 5 months/year. My newly re-made
from-the-ground-up driveway is about 4-years old and has noticeable
spalling.

Can that be "resurfaced"? Would that be just a 'skim coat' or does it need
to be a number of inches thick?

Should I have tried to 'seal' the surface in some fashion? Can I do so now
and reduce future spalling?

We had a stamped/colored patio installed at the same time and the (same)
contractor sealed that with some sort of 'wet look' chemical. Still looks
new.

Appreciate your thoughts. Thanks.