Earlier quoted context omitted.
1. Both iOS Safari and Android Chrome have "Add to Home screen" feature. Is that not enough?
The vast majority of non-technical users have no idea you can do this, and I've even heard many say that didn't know you could do it with any site - e.g. they thought they could only do it if the site had a popup that said they could do it.
Edit: btw, she's a school/music/languages teacher, so she has very little technical background. In her own words, she "touch[es] everything until it works".