Thanks! Do you know if there's a free app? I don't need fine-grained control, just a metred/unmetred switch, and it feels excessive to pay $8 for that.
macOS's APIs and developer docs don't really encourage checking for cellular vs wifi the way iOS's do. So you probably do need relatively fine-grained control to get the same effect, as the vast majority of processes will assume the network connection is either fully up or fully down.
