INSTALL_FAILED_NO_MATCHING_ABIS on Android 9
Even though Google states that this works for the Android 9 and 10 images as well from my experience it works only for the Android 11 preview images.

I have tested this on Windows using the latest default x86 Google enabled images shown in the emulator manager for Android 10 and 11. As test app I used an Telegram armv7 only apk file from 2019:


Android-R - (Android 11 preview) Google Play Intel x86 Atom System Image (revision: 1)


Installation success, app start success

Android-29 (Android 10) - Google Play Intel x86 Atom System Image (revision: 8)


Installation failed INSTALL_FAILED_NO_MATCHING_ABIS



Therefore my results contradict to the Google description you quoted in your question. At the moment only the preview x86 images of Android R seem to be capable of running armv7 apps. 

Test environment: Windows 10 64 bit with Intel Haxm installed.