Google Home or Amazon Alexa interface for person with a speech disability

I would like an application for my daughter who has Cerebral Palsy and struggles with speech that enables her to use a Google Home Mini. She has a Windows 10 PC with speakers, Google Home mini (sited near the speakers) and connected TP-Link Smart Wifi Plugs. The application should enable her to either click a button or type select commands via an on screen keyboard (existing) and joystick which are then spoken through the PC speakers and acted upon by the Google Home device. The application will therefore provide an intelligent Text to Speech function. I have created some very simple (and not very pretty) screen mock-ups in PowerPoint to illustrate what I think the application could look like but am open to suggestions on screen layout and functionality. The ability to store pre saved words and expressions is important as well as being able to potentially change to or add an Amazon Alexa device in the future. I would also like the application to be as configurable as possible through an easy to use interface without requiring code changes. The application could have a web browser or Windows 10 interface and the ability to use the application on a tablet in the future would be nice to have. I have some basic vb / web skills but not the time to create the application myself.