I think one path that could be used and wholy underrated is simply sitting with a user while they use/navigate your application. The user themselves doesn't necessarily need to be skilled tester, and you will need to have more session time than a skilled tester, but it does work and can help a lot.

Also, try using your app/site without a mouse. I've found it funny how many actual, experienced, sighted testers don't actually know the keyboard navigation for things like triggering menus, select boxes, etc. Personally, I don't think I could get used to the voice navigation myself, it's not that it doesn't work, it's just kind of noisy. Although, most sites are excessively noisy visually imo.

Completely agree on both counts. We do usability testing, including with keyboard-focused advanced users.

But usability testing with blind users presents some unique challenges. A past org I worked at ran some usability studies with blind users [1] and while I was only tangentially involved in that project it seemed that subject recruitment and observations were much more complex than typical usability studies. I haven't managed to run a usability study with blind participants at my current org though we have discussed ways we could recruit blind users for studies -- our software is complex enough that we'd need someone who is both blind and a prospective user of our software.

[1] https://www.bloomberg.com/ux/2018/08/28/visually-impaired-wo...