App full screen (or just open) triggered by sensor

Short background for my question:
I’m busy adapting an old “smart” home for a wheelchair bound neighbor, he has limited muscle control. He can use a joystick for his wheelchair but has no fine finger movement, basically he slams his knuckles into his phone screen and can do simple movement on the screen and tap big areas.

He has doors and windows that are automated and are controlled via IR, i’m going to place IR emmiters so that he can control those via HA. I’ll make big buttons for that both physical and in the HA app.

Now the issue i’m walking into is that he has a intercom based upon analog telephony.
He wants an intercom with video and the ability to press a button so the door will open when someone calls (the nurse for example comes at fixed times) , the open door when someone calls is doabale but i want to find an intercom that will work with HA and always open fullscreen on his phone with the option to answer and open the door. Because he has limited muscle control its a pain in the ass to find the icon and open whatever app is bundled with the intercom. And most apps just do a notify on top that he has to reach and press without touching anything else on the screen.

So, is there a way to do this with HA? or is there an intercom out there that goes fullscreen when a call is made?