I'm just going to say, this is probably a post that is going to ruffle some feathers. Mainly because I have plenty of experience with this.
First, as Phantombeta said, it's a matter of there's multiple ways text is rendered and processed. We have to account for mods, and since GZDoom is a game that supports a plethora of modded content - we have to make backwards compatibility a paramount effort. This would singlehandedly, with the scope of the project be the biggest undertaking of the engine - bigger than probably getting it GPLv3 compliant.
One of my partners is blind and she contributes to the work we do extensively at our studio. I haven't asked her about this specific topic (GZDoom hooking into screen readers), but she seems to enjoy just having a more auditory experience when we stream the game our project makes extensive use out of voice acting, rather than relying on solely text-related prompts like most games do.
I know it devastated her to lose her sight and put her into a deep depression, which sometimes hits her like a ton of bricks, and she wishes she could engage in gaming again. This is why I do my best to work within the GZDoom engine to make it so people like Jenna don't have to rely on just a reading experience. And she's completely blind - only able to see basic colors and light. She can't make out shapes. She's been like this since 2017. It's one of the reasons SHDX had such extensive use of voice acting, and we're continuing that for Project Absentia.
My opinion on the matter - mainly from talking to Jenna extensively about her being blind and what she needs from a user friendly experience - is this is a problem with a ton of open source projects - there's not enough funding and not enough dedicated people, and people tend to get it wrong even in an open source environment. And it can be even worse in a corporate environment. You think it's bad in the open source community? Look at Twitch - a company owned by a gigantic monolithic corporation that bleeds their workers dry. Their idea of accessibility? Fucking censoring people because "blind playthrough" is somehow ableist. She doesn't agree with that ruling - and I'm going to listen to Jenna more than some random Twitterite on the matter, frankly. And you got corporations rather taking the issue all the way to the supreme court than funneling money to make their goddamn app accessible to NVDA or Talkback or whatever you use.
That said, she also knows small hobby engines like GZDoom don't have the manpower to implement something like this - it's a community effort, but none of us, myself included, are experienced with how to hook something almost entirely graphical (with no windows form UI to speak of) into something like a screen reader. The best way to do it would be to either fork the engine yourself with people who know what needs to be implemented, or do as I'm doing - work within the framework of the engine and use stuff like ZScript (which powers most of the menus and most game logic) to make the user experience less reliant on text alone.
The thing is, it can be done if people were willing to put effort into it. People who know what they're doing. People who'll listen to people with poor sight - and do more than just polish up mere language. However, it's something that's hard to do when you have a ton of dedicated time and there's all sorts of ways it could be impemented - and it could end up wrong.
I do want to add something though. And this might come across harsh.
I'm actually extremely offended by this answer, on a deep personal level. Your attitude is ignorant, hateful, bigoted, ableist--and most importantly, wrong.
I know I'm not the devs thus it was not directed at me, but assuming everyone here is all these "isms" is fucking stupid, frankly - and I don't care if the devs or the mod teams get angry at me, I'm not going to stand for this.
There are people here who know this shit - I deal with Jenna's condition daily, and she's been having issues with her hearing on top of all this - and I'm deeply worried I'm going to lose her. It breaks my heart. She's never seen my face, and I've visited her twice! And it's a fucking pain to work with apps that aren't coded properly - so it's a crapshoot if NVDA will even work with whatever we have to use for collaboration. I was on a podcast with Jenna recently, and it was 50/50 that NVDA would work with the website we used to do the podcast.
And yes, in WIS, I do tailor the apps we use to accommodate her lack of sight. Even then it's not 100%. It's making me seriously considering moving to Office once we get enough funding just so she can have accessibility - Google Docs ain't cutting it as much as I'd like it to.
So I get it - I fucking get it so goddamn much. It makes me really goddamn sad to see her go through this shit and the only thing I can do is, within my knowhow and what she tells me, try to make her contributions at Waffle Iron Studios count, and to do my best to make my projects accessible to her so she can "see" the fruits of her labor rather than never be able to experience what we've made.
I don't consider it a hindrance. She's my best friend and I love her dearly. And I'm doing the best I can within my means to make things accessible for her. However, it pains me there's only so much I can fucking do with a limited budget. If I knew someone and had billions to spare, you bet your britches I'd point them towards GZDoom and go "hey, make this hook into NVDA please"
I'm getting quite tired of people just assuming because I can't just snap my fingers and make shit happen personally dragging out Jeff Bezos' to sieze his means of production myself, or making everything accessible when I have no goddamn money yet and my programming skills aren't the best aside working with a fork of an engine older than most of my friends, I'm somehow a bigoted monster who wants minorities to fry or some shit. I have fucking limits. I'm just a single person. And I'm tired of this goddamn mentality being prevalent everywhere I go. People assuming the worst out of everyone. It frankly needs to stop.
EDIT: Talking to Jenna about this just now. She says the best way would be to hook a TTS into GZDoom itself, but that'd be such massive overhead from what she's describing to me, and still would be a monumental task. Not to mention, it'd make the software massive unless you choose a proper library for it, or use dedicated speech APIs per system. However, that might be horrible to code given we target tons of OSes - and they all probably have their own.
I also want to state, there is UI scaling available, and I'm working to make sure my project works with this properly.