There is no example specifically for this that I am aware of.
I believe this exists for regular AD but not for B2C. https://github.com/Azure-Samples/active-directory-aspnetcore-webapp-openidconnect-v2
I would highly recommend making a feature request in User Voice, where the product team can respond directly to you. https://feedback.azure.com/forums/169401-azure-active-directory/category/160596-b2c
I am happy to upvote any request that you make if you link it here.