Utilise USERPRINCIPALNAME as a content marker

I've been searching for this and all I ever see is (very useful) answers about Row Level Security, however, I only want to use the UPN in this case as a boolean marker, and not limit the entire report (only a particular page).

in essence I want a calculated column which would return something like
CurrentUser = If([refStaff[Email] = USERPRINCIPALNAME(),1,0)

Obviously - I then run into the whole 'you can only use this as a measure etc etc' but does anyone know of ANY way to return the current user details as a string value, without applying it as a role to limit data across the pack?