USB4/TB4 devices doing (only) PCIe tunneling will absolutely not work on a USB3.2 port, or even on an USB4 port without PCIe support (which you can find on some

USB4/TB4 devices doing (only) PCIe tunneling will absolutely not work on a USB3.2 port, or even on an USB4 port without PCIe support (which you can find on some very recent smartphones I believe. It's spec compliant, PCIe is optional.)