Thanks again to all who participated in this effort! Collect v1.29 is now published with built-in audio recording. The documentation is available at https://docs.getodk.org/form-question-types/#audio-widget.
We have some updates planned for v1.30 based on feedback from @Tino_Kreutzer and others. If you see any issues with this feature or would like to suggest additions, please start a new thread. If the audio qualities provided are not sufficient for you, please join the discussion on a possible high quality option.