Diagnosing Brake Sound

Could use an assist on this one. It's been progressively getting worse for over a year now, and dealership maintains that everything's fine -- pads and rotors seem fine. We can book in a $300 brake inspection, but I'd like to go into it informed. I have a video of the phenomenon*, but can't post due to being a new user. If anyone has a pointer to common "does your car sound like this? here's why!" videos, I'd be very grateful! I guess I can (hopefully?) DM the video link as well.

Some details:
- happening almost always when coming to a stop
- slow rolling stop makes it worse. as does stopping on an incline
- the second set of squeaks is after putting it in park and taking the foot off the brake (no wheel motion)
- mechanic said pads and rotors are in great condition (service 1 done today)
- we don't drive a lot: 47k on the car at this point

Anything else worth mentioning?

* Why is it so hard to find example brake sounds + diagnoses online!!