Greetings!
Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
vWAN enables you to create an Express Route Gateway, not a Circuit. This means that Circuit is not part of the vWAN - only the Express Route Gateway.
If that's clear, then MS Peering only requires an Express route Circuit, not a Gateway.
Since Circuits are never a part of vWAN, it does not matter.
As long as you have a circuit, then you can create an MS Peering.
Hope this clarifies!
Please don’t forget to close the thread by clicking "Accept the answer" wherever the information provided helps you, as this can be beneficial to other community members.