Programmatically using the in-call number-pad while in a call

Question

While I understand that this sort of question has been asked a few times, none of the answers that have been presented have been satisfactory for my needs and so I would like to ask all of you:

While in a call, is it possible to activate a number on the in-call keypad inside of an application? (ie: can I "press 3" or "press 9" programmatically with my application while in a call?)

I have found that it is technically possible via the use of hidden internal APIs (specifically the internal telecom API) using DTMF tones in android, however that will no long be viable when Android P comes into the market (due to restricting the use of hidden and undocumented APIs not standard with the SDK), making that solution the antithesis of future proof.

I also can not request users to use a different default dialer app for various reasons. (I am aware that is also another potential solution, but due to the scope of the application I am working, it is not viable to expect every user to change their default calling application)

If there is another way to do this, I would appreciate the help.