Best grabber with pass through for Paspberry pi

[cornz38]

Ok, so a few years ago i built a hyperhdr but the grabber / splitter whatever was a cheapo RULLZ device from aliexpress, it says its 4k but i suspect it's probably lying. ANyway, one of the cats pulled the cables out and for the last year, it's sat there disconnected so today i decided to revisit it. I've never been able to get the colours right (sp6812leds with natural white). So i decided to do a LUT (no idea) calibration but it failed and now i get some odd error on startup about a driver. I kept getting messages about resolution being too low, so i changed it to the recommended and the grabber grinds to a halt and failed. Now, i get a message about V4L2:USB VIDEO:USB blah blah INACTIVE OR CRITICAL VIDIOC_QBUF ERROR IN V4L2 DRIVER...
So, questions. Whats the best grabber (my tv is used as a monitor and my PC has HDR output) for my needs and is there a way to restore hyper HDR defaults from within the program... Any help appreciated.