VFRnav 4.10.3 introduces a small but powerful improvement for users with connected radio devices:
What’s New?
New: The frequency dial pad is now available, allowing you to manually enter and transmit any frequency — in addition to sending preselected frequencies shown in the app
Here’s the suggestion again to add a button on the dial pad to switch between the active and standby frequency. That would provide all the essential functions for using the radio in VFRnav.