Accessibility is turning into a bigger project than I expected… not sure how to handle this

I’m in the middle of rebuilding a small Shopify site for a client and accessibility wasn’t really part of the original plan. Now they’re asking if the site is ADA compliant because apparently a competitor got into some kind of legal trouble. I started looking into WCAG and honestly I feel a bit out of my depth. I thought it would mostly be alt text and color contrast, but now I’m seeing things about keyboard navigation, ARIA roles, focus states, screen read