Without firewalls rules/port forwarding/Dynamic DNS or personal SSL certificate purchase

I have setup an alternative method of remote access for Home Assistant, I have documented it here : https://www.leadmetomy.computer/index.php/2018/09/02/home-assistant-remote/

Sorry I don’t get this, what is the advantage of this? Isn’t this just a VPN?
Can you do push notifications to smart phones? Can you access your smart home remotely from a smart phone? What about all the integrations that need to access the smart home from the outside, how can they use this tunnel?