Is there a good “catch-all” link that explains in a quick but comprehensive fashion how to implement app accessibility that I could provide to app developers when sending them feedback, especially to developers who, for whatever reason, may not be familiar with implementing app accessibility?
AppleVis Developer Resources Page
We have a great page here on AppleVis, which provides links to Apple’s own documentation and many other useful resources: https://www.applevis.com/information-developers-how-build-accessible-ios-ipados-mac-apple-watch-and-apple-tv-apps
I just give them this website
I just give them apple fizz.com. And I usually tell them that they have resources for developers. And I tell him about all the other things that Apple has does for Apple Accessibility. Including the form.
Tell them to use Google
A quick Google search will yield all a developer needs to add accessibility to their app. If they are really serious about doing that, then they should also be serious about doing the homework and research required, and Google will get them started. So will Apple's developer documentation on accessibility, which as a developer they should already know how to access since it's right on Apple's dedicated developer Website.