Can I customize the primary button in the Cookie Consent banner for Ecwid (by Lightspeed)?

Yes you can customize the primary button. You can customize the primary button from the primary button section at the settings page within the app to suit your needs.

You can watch the screenshot below for more information.

Note:- Changes will be only applied at the storefront if you are on the advanced plan of the app until then it could only be previewed on the setting page.