Yes, this is generally possible. However, it should be noted that the chainrings and spiders from Pinion only fit the standard 9-spline freehub body (singlespeed, 8-/9-/10-/11-speed). The freehub body standards such as XD and Micro Spline are not compatible with the chainrings and spiders.
Fixed gear hubs are not allowed. The permanently rotating chain or belt poses a high risk of injury. The rotating chainring or belt sprocket must be caught up again with every restart in this case. This leads to a very large idle travel when restarting. This results in an unpleasant riding experience.