I think the "send my grandmother non-pixelated photos of my kid using the default messaging app" is a fair ask.

She doesn’t have an email address? You’re not in a walled garden, just self host it and send her a link.

Sure, I can print and mail her the picture, too - the point is convenience. Sometimes, people want to send photos back and forth, too, so asking the technical user of the two to setup a host isn't a solution.

(But I'm guessing you already knew that)