Downloading and installing Google Duo takes all of 30 seconds, and your done.
I text them the Duo link to install. Tell them to click the link, press install, and go through the kindergarten grade setup process which takes all of 5 seconds.
I have done that this year with a lot of family members, that are not tech people whatsoever, and they did it, and now they're very happy to be able to use a FaceTime type app between family that have iPhone + Android
There's just no excuse why people can't do this. Not everyone today is all iPhone users only, there's a ton of Android users too, especially between families. And to communicate this is what needs to be done. And it's very simple and fast.