Use cases

Most customizable toolbar: sort tools, remove sections or single controls, change colours. CDN overlays rarely allow that.
Better PageSpeed than CDN overlays: no remote widget script on every page
Public brochure sites: contrast and text size hosted on your site
Documentation: Read Mode plus speech for long guides
Schools and non-profits: Dyslexia Font and readable font, self-hosted
Brand-sensitive headers: exclude logo selectors so colour modes skip the mark
With Easy WCAG: visitor prefs here, mechanical HTML fixes on the response there

Start with all features on, then disable what you do not want after a week of feedback
Set Skip link target to the real main landmark on your template
Keep cache off on this module
Do not publish two instances on the same page