VPN solution where local administrator is not required.

I'm looking for a VPN solution that does not require user / client is local admin. This is intended for example for consultants at a client who is not a local administrator on their computers.

I wonder if this works, if one avoids setting up a Layer 3 VPN Tunnel with eg F5 APM?

My thought is to set up a portal where I publish RDP links to the terminal servers that the consultants should have access to. I hope I can use one two factor solution with F5, where the customer has a proprietary SMS solution.

Do you know any guidance on how to implement this?

I am grateful for every answer.