IF VPN is based on open source coding can I do my own for free from my mobile phone S9+, and if so, how?
You would have to have a VPN server configured to accept your connection. There are a number of choices out there that can be configured on a home computer: https://www.google.com/search?q=vpn+server+software
Once the server is setup to accept your connection, ports are forwarded correctly, etc. you'll need to set up your phone to use the VPN connection. https://www.verizonwireless.com/support/knowledge-base-216597/
PS, I hope you didn't sign up and ask this question in hopes to link to your product. We're overly cautious when a username matches a potential product or service.