there are no templates to support vb.net, and it may be missing required compiler features (vb.net has not committed to supporting all .net runtime features and is currently missing some). also all the maui code generators all generate c#, so you would need to manually convert each one vb.net.
you should be able to use vb.net based library projects in a Maui application, but all the UI code should be c#
note: this is the same story for asp.net core. at this point vb.net is a legacy product.