I don’t know for sure, but if I read that comment correctly, those six companies are turnkey suppliers for the large computer brands.
“Proudly Made In Japan. VAIO, and authentically Japanese manufacturer, can boast of in-house design, manufacturing and support teams. Our level of commitment to Japanese technology and aesthetics that is a hallmark of VAIO’s craftsmanship.”
There's also a government shopping site for approved "MAS IT Schedule 70" desktops and laptops: https://www.gsaadvantage.gov/advantage/ws/search/gss_search and some of those say "Made in the USA", but I'm not sure of the extent of vetting they do of those component parts. They're mostly Dell and HP machines, but those vendors might have special pipelines for getting those special USA machines...? Not sure.
A potential downside might be that you're limited to macOS or Linux only.
Though they seem old and overpriced. Not much left of Toshibas former glory. (For some models only anyway)
edit: https://us.dynabook.com/