Starling 2 Max already has 4 or 5 cameras (depending on configuration - 5th could be a TOF sensor if selected). There are two high resolution IMX412 cameras (up to 4056x3040 resolution rolling shutter RGB cameras) and there are two AR0144 monochrome global shutter cameras that are used for feature tracking / VIO (1280x800 resolution).
If you really wanted to, you could add two more high resolution cameras to VOXL camera port J8 (camera ports J6 and J7 are fully used up). Adding the first IMX412 camera would just require you to buy a camera with the correct adapter, such as M0161 camera (with ucoax cable) and M0155 adapter which would plug in to VOXL2's J8. In order to get two IMX412 cameras added to starling 2 Max, it will be a bit more complicated, including a small Kernel change.
It looks like you are potentially looking to re-configure cameras on Starling 2 Max, so my suggestion is first to understand the capabilities of the cameras you have (resolution, field of view, etc) . The lenses on the IMX412 cameras have about 120 degress of horizontal FOV (and you can check it) : https://www.modalai.com/products/msu-m0161 . So for full 360 degree coverage, you would technically only need three of these cameras. However, you have a total of 4 cameras already and the lower resolution AR0144 cameras also have a wide FOV (almost 140 degrees horizontal : https://docs.modalai.com/M0166/) and can be used to supplement the two high resolutions cameras.
It seems to me that you could take the cameras that you already have and build a hardware mount for them. Also, as Eric said you might want to consider using VOXL2 for whatever you are trying to do on the Raspberry pi, since VOXL2 runs Ubuntu linux (but no display).
In terms of USB adapters, your startling 2 max already has a wifi module that uses a USB2 adapter, so you can plug in an ethernet adapter instead of that wifi dongle. BTW M0151 adapter board (which is part of Starling 2 Max, this is were the wifi dongle is plugged in) supports USB 3.0 : https://www.modalai.com/products/m0151
Alex