No, this is incorrect. The GrapheneOS NetworkLocation client (https://github.com/GrapheneOS/platform_packages_apps_Network...) is using Apple's request format and performing the calculations locally, similar to how it's done on iPhones. The proxy is just an entry in the nginx config: https://github.com/GrapheneOS/grapheneos.org/blob/main/nginx...

The data is cached for roughly 15 minutes. https://grapheneos.org/features#:~:text=It%20caches%20the%20...

GrapheneOS plans to scrape Apple's database and make it downloadable, so Wi-fi positioning could be done fully locally.