andreamarucci wrote:but I'm searching for a solution that's not linked to a plugin someone has to update regularly. Do you imagine another possible solution to achieve that other than the plugin?
I'm not quite sure what you are thinking of. Regardless of if it's a "plugin" or just some PHP code (which would only be a case of definition), it needs to be a PHP solution created for Xenforo. You can't just add anything PHP into Xenforo unless it's created (or adapted) for Xenforo, just like you can't add anything to Wordpress unless it's created or adapted for Wordpress. To be honest, the PHP itself for this seems quite simple, but the task also includes figuring out how to include in Xenforo as custom PHP / plugin ... and do you need some admin capability? I could perhaps take a look for a minimal fee.
Embed is "different" because it's javascript-based and connects directly to Files app (PHP), so does not need any specific integration with xenforo. However, it still takes some patience to setup and it doesn't sound like exactly what you are looking for.