We have a VF page with an iframe to another platform's react app.
In the VF page, we get the session id by calling GETSESSIONID() and passing it to the react application, which uses it to make Salesforce API calls.
In my lightning experience, this works perfectly. However, this is not the case within the community experience. The error message is "ERR FAILED 401 (Unauthorized)".
Is there any way to obtain a valid session id in the community to use for SF callouts?