hello diverger,
please access Jetson Xavier NX Product Design Guide. you should see [Chapter 9. MIPI CSI Video Input] to setup camera connections.
please also check the reference driver without i2cmux, define the camera node under I2C directly,
for example,
$L4T_Sources/r32.6.1/Linux_for_Tegra/source/public/hardware/nvidia/platform/t19x/common/kernel-dts/t19x-common-modules/tegra194-camera-e3326-a00.dtsi