Hello!
I'd like to help you with this task.
I sujjest you to use OpenVPN, it's strong, flexible and good VPN protocol. To use it as tunnel broker, your VPS ISP should give you 2 IPv6 subnets, 1 will use on VPS, 2nd will be routed via VPS IPv6. Mostly it's not possible, providers don't give 2 subnets, or don't want to configure routing. Can your ISP give you second routed subnet?
I have big experience with OpenVPN servers\clients. Experience with variety of different configurations OpenVPN servers, such as serial connection 2 or 3 OpenVPN servers, for maximum security. OpenVPN over IPv6 protocol. I have big experience with network administration and pfSense. Experience with VMWare ESXi, MS Hyper-V, Proxmox VE, Mikrotik, Ubiquiti and some different skills.
My another skills and reviews you can see in my profile.
Hope for cooperation!
Thank you!