Vision impairment is a spectrum, so someone who can see to some extent may be using a screen reader to assist. People might be using your site at 150% zoom, etc etc.

One thing you can do is put a note somewhere easy to find that says "if you require assistance using this site, email someone@domain.org". Sites that I've worked on also had a phone number here but I understand that's an edge case.

You also mentioned alternative ways to get information - if there's ones you can link to (without linking to a competitor or whatever), there's no reason not to provide links.