Yes, according to my research, the H6 housings are fully compatible. I found the following information from the manufacturer:
Display the centrepiece of any PC with pride. Set up your GPU vertically and provide ample space for cooling and stability by using this solid steel bracket designed for the H5, H6, H7* and H9 series.
Robust steel bracket holds GPUs vertically and prevents sagging 175 mm PCIe 4.0 riser cable is flexible, backwards compatible and supports high-speed data transfer Fits perfectly with NZXT H5, H6, H7* and H9 series cases and colour schemes *Not compatible with the latest H7 Flow and H7 Flow RGB, only with the H7 models from 2022.
