I'm not sure. I use Android. Just search 5th edition character sheet. And, it already has a lot of the precursors available so he would pick his race and class and everything can be filled out right on the app. It's a lot of drop down boxes. Also, it is free to set up your character however, to level up you have to do a one-time payment of $3. Also, when you get a new gear equipment and weapons excetera it does allow you to add those to your character sheet. And, you do have to alternate between page has to get to the different aspects of your character but you get used to it. Let me know if you have any other questions :-)

text files are nice because they open quickly and edit responsively. HTML-based material is certainly my go-to for reference: screen readers support better find options within web content, and good structure (headings, tables, lists) etc can make things really nice.
JAWS has place markers, which can be useful, and you can even do clever things with javascript if you need to.
I suppose much of it will come down to your player, though. i'd advise starting off with an export from Word/Docs to plain html and see how that goes.