Hello crwilliams,
Thank you for using Apple Support Communities!
I understand from your post that you have been unable to have Siri speak your text messages while using your AirPods. This feature is due to come out later this fall as announced in a footnote at the bottom of this article:
iOS 13 - Features - Apple
"Coming later this fall. Works with second-generation AirPods. Siri is available on iPhone 4s or later, iPad Pro, iPad (3rd generation or later), iPad Air or later, iPad mini or later, and iPod touch (5th generation or later) and requires internet access. Announce Messages requires apps to be developed with SiriKit. Siri may not be available in all languages or in all areas, and features may vary by area. Cellular data charges may apply."
Best Regards.