I'm new to iRules, i'm looking for a iRules who can can return an URI from a VIP

Can you try this example to rewrite the Location header value to the fully qualified domain name that resolves to the VIP and see if this is what you're trying to achieve?

when HTTP_RESPONSE {
   
   if {[HTTP::is_redirect]}{
      set virtual_ip [clientside {IP::local_addr}]
      set domain_name "host.example.com"
      set location [HTTP::header value Location]
      HTTP::header replace Location [string map [list $virtual_ip $domain_name] $location]
      log local0. "Updated Location header: [HTTP::header value Location]"
   }
}

If that works, then you can use a version with less variables and no logging:

when HTTP_RESPONSE {
   if {[HTTP::is_redirect]}{
      set domain_name "host.example.com"
      HTTP::header replace Location [string map [list [clientside {IP::local_addr}] $domain_name] [HTTP::header value Location]]
   }
}

Aaron