1970 house in west Houston, have had small cracks in drywall since remodeled in 2016 and after Harvey. Nothing major till around beginning of this year. Cracks have appeared all over near middle of house. Some cracks are 1/4" to 3/8", seems like house is separating right down middle part of house. Doors not closing anymore. I know the drought is not helping this year. I grew up in an old house on blocks so cracks were normal and just part of it. Not sure if I just repair the cracks or I have a foundation issue. Who could I get to evaluate? I'm sure any foundation repair company will just tell me they need to repair it.

Correct. Foundation repair companies are a hammer in search of a nail.

To get an objective opinion, hire a structural engineer. I'm sure if you do a forum search for structural engineers in Houston, you'll get some hits.

We are in a 10 yo old house in Austin. Cracks started showing up a couple of years ago. We just had a foundation review/survey done. They measured elevation variances of whole house. They concluded the variances are due to seasonal (Summer) conditions and all within expected limits, even the -2.5 inch one.

I have reached out to Nevins Engineering to evaluate. He did the design for a lvl beam I added during remodel.

If I were a betting man, Aggieland volatile soils effect on a 70's foundation in a drought exhibiting wide earth cracks this month might be similar to what you have ... and what the structural engineer will report (Kudos for hiring him).

Center of foundations that are not slab on deep piers usually stay moist, as the rest of it dries out from outside in.
Thus the support soils dry up like a kitchen sponge, so as support gets less = less height of foundation at edges, "hump" in center and everything on top exhibits what is being telegraphed to it. Cracks.

Usually the prescription will be slant piers to jack up perimeter, with free adjustments but only for a couple of years.
Others may elect a perimeter soaker system but this works best with
a. several monitors to insure equal moisture all side of foundation
b. city doesn't curb water usage
c. extra water bills, perhaps mitigated by your new garden aesthetics that also benefits

Sometimes a seasoned landscaper can mitigate a lot of cracks by digging a deep mulch/garden bed at least the West foundation corner (usually the driest one) for you to direct gutter runoff, keep wet for his plans that a) like wet feet + b) help shade that area

Does the yard have a sprinkler system and are you currently using it?

Yes and yes.

Blair is a really good guy. I used to live across the street from him. He actually did a similar assessment on a house my wife and I bought 4 years ago.

Could also be your framing members.