I’d recommend this site: https://webaim.org

Aria is still useful. For example; you can give the screen reader user alert messages when they’re reaching the character limit, or if an item has been added to their basket.

I'm not an advanced web developer, but generally speaking, a lot of the normal HTML elements just work for us. I always point out three major issues (I need to just make a draft for this).

1. Lack of headings or landmarks before important info, or overuse of headings at improper levels. As a great example of this, I recently found a CNN article with a level 1 heading for the article, 32 related articles under level 3 headings, and then the start of the text, with nothing before it. This forced me to choose between scrolling through every heading or going to the last one and hoping it would get me where I needed to be. Things like <main> and <nav> are also helpful.
2. Don't make unlabelled bits of text and stick an onclick event on them. This can often cause problems, and it takes away information such as seeing which item is selected in a list of possible options. It also makes it way more likely that dropdown menus won't populate their contents right below the button that opens them. This kind of thing is where Aria roles can come in handy if you really do need to use a regular <span> or similar.
2.5. Clicking something on one part of the page shouldn't cause another part to silently populate itself with something new. If you have to do this and can't find a way to make the content show up after the button, perhaps consider a pop-up dialog box that keeps focus inside it until the user chooses the right option.
3. Something important to the page content should never be an image with no text label. (I know this is probably an obvious one, but I have to include it here.)
It gets more complex with the big monstrosities, and I really appreciate you doing this. I've seen a few posts like this one and it's very encouraging to see developers working on these things, because it really is a big barrier still.

you are going to have to learn how to use NVDA or JAWS. they are the screen readers that blind people use. you can do all the research and testing you want but without using actual screen readers to test your work you will never really know for sure if you did it right.

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learning how to use a screen reader can be a little intimidating at first because its navigating the internet with just a keyboard, no mouse. you do get the advantage of being able to cheat by using your monitor though.

If you follow Web Content Accessibility Guidelines as best as you can, use HTML 5, and use Aria anywhere you need to use a JS widget or funtion, you'll have a very smooth and easy experience for all users who need to interact with your site using any assistive tech, not just us blind users. HTML 5 semantics does not account for custom JS controls or functions, which is where Aria must be used, plus browsers and screen readers adapt with every release to attempt to follow new methods of labeling and programmatic association and discernment.

If you aim to make your sites WCAG 2.0 Level AA compliant, you'll be in a very good place.

The surveys from $1 can also help you understand what screen reader users actually tend to find important, VS the regulations them selves. I mean both are useful, and if your building a website for low vision people as well that won't help you, but it may save some time at least.

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And I will be the third to suggest picking up a screen reader and doing some hands on testing with it, as web devs who take that step seem to be the most successful in integrating true accessibility. There is nothing quite like walking in someone else's shoes and understanding firsthand the frustrations that certain design choices cause. Helps you empathise on a personal level and gives you extra drive to get it right.