@Jenkler you can customize the nodebb-plugin-sso-facebook
to make it happen
add this code before this line https://github.com/julianlam/nodebb-plugin-sso-facebook/blob/master/library.js#L148
user.getUserField(uid, 'picture', function(err, userPicture) {
if (!userPicture) {
// Save their photo, if present
if (picture) {
user.setUserField(uid, 'uploadedpicture', picture);
user.setUserField(uid, 'picture', picture);
}
} else {
if (picture && userPicture !== picture) {
user.setUserField(uid, 'uploadedpicture', picture);
user.setUserField(uid, 'picture', picture);
}
}
});
one warning though... even if the user changes to use default icon in their profile, this will switch it to facebook pic on login