sort other fields on user page?

ah, found it:

/*
 * Make our "Registration date" column sortable
 * @param array $columns Array of all user sortable columns {column ID} => {orderby GET-param} 
 */
add_filter( 'manage_users_sortable_columns', 'rudr_make_registered_column_sortable' );
 
function rudr_make_registered_column_sortable( $columns ) {
	return wp_parse_args( array( 
	            'user_registered' => 'user_registered',
	            'wpmem_reg_ip' => 'wpmem_reg_ip',
	            'user_id' => 'user_id'
	                        ), $columns );
}