OP your experience isn't unique. It is quite slow and can be inaccurate. Especially outside in the sun. It's summer here where I live and it's very bright/sunny - so you can forget about the fingerprint unlocking reliably. If it's in direct sunlight, it absolutely won't unlock for me. I either have to go somewhere with shade, cover up the screen with my other hand, or do what I do and just enter my PIN number.
It's a hardware and software issue. The fingerprint hardware (optic fingerprint scanner) Google opted for is older and isn't as fast/accurate as the latest fingerprint sensors (ultrasonic fingerprint scanner). And on top of that, even other phones with the same optic fingerprint scanners as the Pixel 6, are still faster to unlock, so that's why it's also software issue. Whatever Google are doing to run the fingerprint scanner is slower than other optical scanners. Google claim it's about security, but the Pixel 6 can still be unlocked with other people's fingerprints, so it's not completely safe anyway.
It sucks but it's how it is. I do believe Google could improve the speed even further, but I don't know if they can improve the accuracy and don't think they can improve the functionality in bright light.
Here have a read about the fingerprint scanner with some tips on how to improve it:
https://www.androidpolice.com/pixel...xplaining-the-problems-how-to-make-it-faster/
Android Police were bang on the money when they called it "the slowest in-display fingerprint sensor on any flagship right now". It absolutely is.
Hopefully Google choose a better fingerprint scanner in the Pixel 7.