I can use my XR Elite without battery direct connected to my PC (front USB-C) with the 5m VIVE Streaming Cable.
Works without any problems.
I have a Asus ROG Maximus Z790 Extreme motherboard.
It have a USB 3.2 Gen 2x2 PD 3.0 / QC 4+ support for up to DC 5V/3A 60W.
Only works if you connect the 6-pin PD_12V_PWR connector on the motherboard. (It’s the same as a PCI-E 6-Pin GPU cable)