Based on what you’ve shown in the two videos and written in this post, I doubt it. I don’t think your problems are actually on the video end but rather on the USB side. The USB needs to power the headset and enable the video. It acts like it’s running out of power whenever it tries to power up the rest of the headset and rebooting over and over.
The splitter cable you purchased doesn’t necessarily actually combine the power from both USB ports onto the fiberoptic cable. There are complexities to USB power, and I’d actually be a little surprised if that just worked as intended unless the specific type and brand of splitter cable has been tested to work in this specific use case with the fiberoptic cable by someone who actually has the equipment and expertise to tell.
I also notice that you have a whole steering wheel setup with what looked to be a direct drive motor. The RF interference produced by these motors is known to cause problems with VR headsets, particularly with Pimax. So the first thing I’d recommend is unplugging and disconnecting that steering wheel setup completely. In fact, you should unplug all other USB devices from your PC besides minimum mouse/keyboard and retry testing. It could be not working either because of RF interference issues or power draw from other USB devices.
The next thing I would try (while maintaining everything else disconnected) is connecting the fiberoptic’s USB through a powered USB hub by a trusted brand such as Anker. If not enough power is the culprit, this should definitively eliminate that as a possibility.
My next highest suspicion would be that it’s a bad fiberoptic cable.
Unlike the 90Hz problem, I do see some possibility that the repeater will help here, but I give it very low chances. I’d try replacing the fiberoptic cable first. However, if the reason you want the fiberoptic cable is the additional length, the repeater would provide that with the standard cable you say works, and you could just avoid the problem that way.
Also, if you haven’t opened a support ticket with Pimax, that’s actually what you should do first. You could try these other things in parallel, but I’d consider whatever advice Pimax support has about it to be the mainline toward a working solution.