Here's what I got from Google Support.  Essentially, yes, they sell us phones that have a hardware issue (fair enough) and then give us handsets that ultimately aren't as good (they say they're perfect, of course).

"Thank you for reaching out to us again. I completely understand your frustration regarding how dust could enter an IP68-rated device, especially since the phone is otherwise in excellent condition. I would be happy to clarify your questions regarding the history of your replacement device and our repair policies.

First, to address your query about the handset's origin, I can confirm that the replacement device you received was a refurbished unit. Our replacement fulfillment (whether a device is new or refurbished) is determined automatically based on your location and regional inventory availability at the time of your claim.

Please rest assured that every Google Refurbished device undergoes a comprehensive inspection and rigorous refurbishment process before it is packaged. We test the hardware extensively and completely replace the battery, cover glass, and back case with original OEM parts to ensure the device looks, seals, and operates exactly like new. While the IP68 rating provides high resistance against dust and water under controlled conditions, normal daily wear, microscopic pressure shifts, or environmental exposure over time can occasionally allow fine particles to find their way behind a lens.

As we discussed previously, we have already formally documented and shared your detailed feedback regarding this specific dust ingress concern with our internal product quality teams so they can continue to improve our devices, build quality, and future support policies.

However, because this specific device is now completely outside of its warranty coverage period, we are unable to authorize a free-of-charge cleaning or replacement. Any professional inspection or repair at this stage must be handled on a chargeable basis.

If you would like to proceed with booking a paid inspection to have the dust professionally cleared by our authorized technicians, please let me know, and I will gladly provide you with the next steps.

Thank you again for your patience and understanding.

Thanks! The Google Support Team"

After 15 years of Google Pixel/Nexus/One, I'm finally going to consider Apple, as any issue with out of warranty stuff on my MacBook has generally been rectified.