It may seem challenging to educate your technologically challenged grandparents about Bitcoin, but that doesn't mean it's impossible. Instead of feeling overwhelmed by the task, try finding a comfortable and convenient location, such as your home, to discuss it with them. And if you're still determined to explain it in person, consider using visual aids like a computer or smartphone to make the concept easier to understand. Remember, it's often more effective to teach someone directly rather than relying on intermediaries.
It is not only challenging but also very difficult. But if I were in that position, I would prefer not to teach them (grandparents) about Bitcoin and would rather let them pray or rest more. Because with their old condition, it's actually time to no longer burden their minds on work they still don't understand. But if they still want to know about this (Bitcoin), then the solution you offer I think is very appropriate for this.