Yes, you can use first-party models on the Pixel NPUs or you're stuck with NNAPI which is self-admittedly deprecated by Google and doesn't work all that well.

On third party model workloads, this is what you will get:

https://ai-benchmark.com/ranking.html

https://browser.geekbench.com/ai-benchmarks (NPU tab, sort w/ quantisation and/or half precision)

Google is clearly not serious on Pixels in practice, and the GPU performance is also behind by quite a lot compared to flagships, which really doesn't help. CPUs are also behind by quite a lot too...