I think it depends on the specifics on what your looking for, you can gain the most control by making your own route tough, the users route is more meant to list out users, not exactly search them as there is a pretty crazy amount of stuff you could be wanting to search based off of, and doing that all through parameters might get difficult.
I am not saying it cannot be done, I just found personally that rather then fighting to get a route to follow your use case, building out custom routes is easier.
Here is an example:
// namespace is like app/v1 rather then wp/v2
register_rest_route($namespace, '/users', array(
'methods' => WP_REST_Server::READABLE,
'callback' => 'get_user_list',
'show_in_rest' => true
));
then for the function get_user_list
function get_user_list($request) {
//below you can change to a WQ_Query and customized it to ensure the list is exactly what you need
$results = get_users();
//Using the default controller to ensure the response follows the same structure as the default route
$users = array();
$controller = new WP_REST_Users_Controller();
foreach ( $results as $user ) {
$data = $controller->prepare_item_for_response( $user, $request );
$users[] = $controller->prepare_response_for_collection( $data );
}
return rest_ensure_response( $users );
}
Of course there is more too it (like pagination).
https://github.com/WordPress/WordPress/blob/master/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php
will show you how it builds the standard route through the get_items function. Depending on what you want to query by it could also tell you the options you need to query by (if using the default route).
The only reason I am giving such a complicated answer as it could help you learn the ins and out of how it works and what application of the REST API might suite your needs.
