Hi Ronnie,
I have to admit I didn't have any luck finding anyone in my usual sources who sells just the physical buttons themselves. The closest I came was a Reddit post where a guy ended up taking a chance and buying the buttons for a Pixel 7 to replace a missing one on his 6 Pro and reported that the button fit perfectly. Unfortunately he was talking about a volume button rather than the power button, so it's not really an answer, more of a lead. Here's the thread.
[link|https://www.reddit.com/r/GooglePixel/comments/rtpajq/pixel_6_pro_volume_button_fell_off/|Pixel 6 Pro Volume Button Fell Off : GooglePixel|new_window=true]
And here's a link to the eBay listing that appears to still be good.
[link|https://www.ebay.com/itm/374392831131|For Google Pixel 7 7Pro Pro Side Button Keys Power Volume Buttons Replacement|new_window=true]
That's the closest I can come; let us know what you end up doing, as I'm invested in the subject since I have a 6 Pro myself.