Gemini 2 was entirely trained on Trillium, Googles 6th generation TPU. About 100,000 of them. And all inference is run on TPUs.
https://venturebeat.com/ai/google-new-trillium-ai-chip-deliv...
https://venturebeat.com/ai/google-new-trillium-ai-chip-deliv...
Sample size of 1, obviously, so YMMV.
I also pay for Claude Pro for personal coding use, so I'm aware that Flash isn't exactly a drop-in replacement for a more powerful model. From my limited testing, though, Pro 2.0 is almost indistinguishable from 3.5 Sonnet.