Short answer
HubSpot's developer guide covers text alternatives for non-text content (empty alt for presentational images), visible form labels instead of hiding them, a skip-to-content link, keyboard navigation, and semantic elements like proper table headers. HubSpot's KB adds that alt text helps both accessibility and SEO.
1. Pages
Website pages in my demo portal.
2. Legal compliance
Whether a site meets a legal standard depends on more than HubSpot settings. Get a specialist audit if it matters to you.