Hi @Samuel Hjelmfelt ,
SharePoint is not a public site and is very careful about permissions. Users need to join the organization through a Microsoft account and then access resources according to their permissions.
For external users, SPO has also established some sharing methods. And as Trevor mentioned, it is not a suitable platform for anonymous users.
External sharing overview
Per my understanding, displaying SPO pages on a customer portal is currently not supported using OOTB features.
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