This is entirely untrue. Almost anywhere you live in the U.S. you can find local brands with local production.

Where can I find an oven made with entirely US parts (or even ~85-90%+)?

I'll tell you in advance that I haven't been able to locate one in a few years of looking. Most major appliances are, at best, 60-80% american with no accurate accounting, even if they're "assembled in the USA". Cars are the only thing with accurate sourcing labels due to legislation.

And the local production is an assembly of something really made in china.