Redirect domain and subdomain to rewrited rule depending on $_SERVER['REMOTE_ADDR']

Question

In first question : Must or do I have to use .htaccess rather than wp redirect ?

I’m loolink for to use wp_redirect() to redirect website to new permalink structure for language. Is it the good function and solution ?

I use add_filter('rewrite_rules_array', 'my_rewrite_rules', 11); to rewrite permalink and insert region code (fr,en,de,es,etc) just after domain.

Example permalink : https://subdmain.domain.com/en. Both of Subdomain and Domain must be included .

Currently the new permalink structure work only manually. What I use :

function langdb() {
    $atvlg = array('fr','en'); 
    $displang ='';
    foreach($atvlg as $keylang => $valuelang ):
        $displang .= $valuelang;
        $displang .= next($atvlg) ? '|' : ''; 
    endforeach;
    return $displang;
}

function my_rewrite_rules($rules) {

    $listlangs = langdb();
        $new_rules = array();
        $subdomain = 'https://' . $_SERVER['HTTP_HOST'] .'/';
        $new_rules['(?:'.$listlangs.')/?$'] = $subdomain.'index.php';
    
        foreach ($rules as $key => $val) {
            $key = '(?:'.$listlangs.')/?' . $key;
            $new_rules[$key] = $val;
        }
        return $new_rules;
    }
    
    add_filter('rewrite_rules_array', 'my_rewrite_rules', 11);

I detect region code from $_SERVER['REMOTTE_ADDR'] and curl call. From this region code I want to redirect automatically visitor depending on the language provided.

I try this code but it doesn't work:

$visitorlang = strtolower(getusercountrycode());
    function atv_redirect(){
        $atvdomain = $_SERVER['REQUEST_NAME'];
        $currentpage = $_SERVER['REQUEST-URI'];
        if(!is_admin()){
            ob_clean();ob_start();
            wp_redirect($atvdomain.'/'.$visitorlang.$currentpage);
            exit;
        }
    }
    
    add_action( 'template_redirect', 'atv_redirect' );

here is first rewrite rules:

array(122) {
  ["(?:fr|en)/?$"]=>
  string(30) "https://domain.com/index.php"
  ["(?:fr|en)/?^wp-json/?$"]=>
  string(22) "index.php?rest_route=/"

This rules works in htaccess but I don't know how to include subdomain I rewrite rule.

RewriteCond %{HTTP:Accept-Language} ^fr [NC]
RewriteRule ^(index\.php)?$ /fr/$1 [R=302,L]

Once I understood regex I would like to reproduce this htaccess code using wordpress functions to add_rewrite_rule to all wp site generating language depending on $_SERVER['REMOTE_ADDR']. I already got the region name from IP.