I installed the washer system this morning. I use GM p/n 84606448 and roughly 18" of 5/32" ID rubber windshield washer tubing.
84606268 appears to be the hose which connects to the camera nozzle. The fitting is a larger size than the camera housing Infotainment supplied with my camera, likely due to a mid-generation change by GM. I attached my generic 5/32" hose directly to the washer nozzle. This also required removing a fitting and last segment of hose from 84606448.
84601635 is also not required, and I don't see how it could be used in any installation of the camera washer. These are the 3 parts are currently listed on the "Things to know" tab of the product page.
https://infotainment.com/shop/exterior-accessories/digital-rear-view-mirror-cameras/g-bdlcammir-21suv/
My generic 5/32" rubber hose attached directly to the camera washer nozzle. The nozzle is intended for a push on fitting and has a semicircular profile bump rather than a triangular profile of a hose barb. The hose is quite secure as I mistakenly thought I had to remove the hose at one point.
Compared to stuffing extra wires through a grommet, it was relatively easy to shove the camera lead and washer hose through this one, which is sized to have those options from the factory.
I removed this fitting and section of hose from 84606448. I also removed the retention clips to allow it to fit through the grommet between the hatch and body.
My generic 5/32" hose fit this perfectly.
Jeff