For most e-commerce teams, the fastest path is to fix shared components before page specific issues. Buttons, inputs, dialogs, autocomplete controls, banners, tables, accordions, and focus management patterns affect dozens of templates at once. Once those are stable, move to transaction critical pages and then to content scale issues such as media, downloadable documents, and help content.
EN 301 549 gives you a way to turn legal outcomes into engineering work. For web and app journeys, map applicable EN 301 549 clauses and WCAG success criteria to each user flow, then link those requirements to component level acceptance criteria, test cases, defect logs, and release sign off.