That sounds like a pretty cool job!
It is! It's a growing field, too, so anyone who knows semantic HTML well and knows CSS and Javascript well enough not to be freaked out by looking at pages of code should consider getting into this line of work. I spend my days navigating websites via keyboard and screen readers and doing some poking into the main HTML code to see where it's falling short and not meeting the Web Content Accessibility Guidelines 2.1, level AA success criteria. I write up lists of what's not meeting the guidelines, give recommendations for each problem I record, and then we send it to our clients so they can tell their devs or whatever web development company they hire what needs fixing. It is amazing how little of the internets is actually accessible for people who have disabilities, temporary or permanent.
I used to teach college-level writing, burned out, and went looking for another job. I was
amazed when I managed to find this one, which is both in demand and lets me help to make the world a better place for others. I didn't think I'd manage to find that sort of unicorn job!
Edit: if anyone's interested, send me a PM and I'll link you to some of the resources that can help you get started. It's easier than people think, and main problem we're running into right now is that web and app developers often think of accessibility as an add-on rather than taking it into account from the start.