It’s detectable and has been known to result in account bans. People have been doing it since the early days of Gemini, when the ToS was still unclear, and some only found out after their accounts were banned. There have been multiple GitHub issues and reports to Google about it. It’s not worth the effort unless you’re willing to risk a secondary Google account.
And if I am not mistaken, Theo’s T3Code (which was explicitly told was bad), doesn’t even use anything else than AI producer provider command line tools and use them with `-p`.
That line of reasoning has no end. If you use Antigravity on anything other than a Google Chromebook or Pixel, the hardware is a 'product not provided by them'. Is that a TOS violation?