I don't have much experience with XCode, however the few things I did do seemed accessible. As accessible as XCode can be - I personally find a lot of the interface a bit confusing. Super long lists, nested options, but I assume those aren't things that are specifically confusing to people using assistive tech and I'm sure I'd be able to find my way around it well if I used it more. Mac seems to be a lot more consistent with their accessibility story than others, and we constantly get new features from them. With the new MacOS for example we got a VoiceOver feature that tells us when we have formatting problems in text, and we can finally get indentation announced (something which we had to do using custom scripting before).
Not to mention all the cool things that involve some form of (live) image recognition, like telling us where people are, where doors are, etc etc.
