We need the Steps to have the Task resolved regarding: How to publish SharePoint calendar on a public website.
We were only able to enable the anonymous access from the calendar to access and not sure how to publish SharePoint calendar in our website.
Karley Zhou-MSFT
On
It is not feasible to embed a SharePoint calendar on a public website. The SharePoint calendar requires a login to the SharePoint account before viewing to prove that the visitor has permission to view the calendar. This is for security reasons and SharePoint adopts this behavior by default.
Checking on this article, it seems sharing your SharePoint calendar to a public webpage is not recommended and is not made to be publicly accessed. There are workarounds provided, one is depending if the calendar is on SPO or OnPrem, if SPO you have to create a web service with access on returning content. You can't share directly due to not being able to share without logging a user in. If you're using SPO, then you have to make the Sharepoint site accessible by anyone.