In terms of accessibilty, iPhone is pretty much the best bet. Unfortunately, it's also a pricey option, especially if he is dead set on an amoled screen.

Any chance he can wait until the fall? They should be announcing an upgrade soon and the prices would fall.

If not, it may be possible to buy a refurbished iPhone X, although I don't imagine that comes up often.

IPhone is the best as far as I’m concerned. It isn’t that hard to learn to use all the features. I bet he could adapt.

I notice that you said that he believes that the amoled. I am going to suggest something that I think others are pointing to as well. Perhaps he does not need amoled. It sounds like his vision is not great. With an iPhone 7 he could likely read and respond to texts and emails much more quickly without looking at the screen at all. That way he will get a break from straining to read or dealing with light at all. Just because he has some vision does not mean he has to use it all the time. It may be worth going to an apple store and experiencing voiceover in action if he has not already. I should also say that I mentioned iPhone 7 but voiceover also works on older models that would be cheaper.

Go to eBay get a 7 or 7 plus for 200 off retail. iPhones are best for accessibility have great screen reader too if needed

Your friend might find it useful to create a list of requirements with points for relative importance. Together you can then score different phones against each want and need. He can then look at the numbers and pick from the top scorers as he prefers.

My concern is that he is making the "amoled" feature a blocking requirement and all the other benefits of iPhones accessibility aren't being fairly accounted for.

You said he reads lots of PDFs. Take a look at Voicedream Reader.

http://www.voicedream.com/

This app will convert a PDF to text and read it out loud while showing the text on screen with a high contrast highlighting of the words as they are read (synchronised highlighting). This is useful for someone who wants to read the text while it is being read out to them. Available on Android and iPhone. My only connection is I know a satisfied user.

There may be other apps available (e.g. Seeing AI) that tip the balance.

Honestly, if he needs accessibility, iPhones are gonna be the best for him. Apple set the standard, and few companies live up to it.

If he's losing vision as well, it'd be best to be used to the most intuitive screen reader, rather than buying an android and then trying to learn talkback, which is usable... mostly.