Advisor to spend some funds to buy things that make group members feel better working at home. Is it selfish to request a tablet and stuff?
Surely these are precisely the sorts of things that your advisor envisaged buying when they offered to get "items to make you more productive or happy working at home"? A decent monitor (and keyboard, and mouse) for your laptop are fairly essential if you're going to be using it all day every day for the next N months. A tablet is perhaps a bit more of a luxury, but hardly excessive. Remember, as a fraction of the total cost of supporting a PhD student, an iPad is small change.

If you're concerned, phrase your email making it clear that you are presenting a list of suggestions rather than demands, as you're not sure how much money the advisor will want to spend.