Dan, I recently installed my Starlink DISHY. I live & work out of my RV full time, but I believe the process is essentially the same. Apologize for the length of this post.
The 1st thing I would accomplish is to get the Starlink DISHY functioning with either the Android or MAC app. It may or may not take a little time due to firmware upgrades or how populated your area is. Be patient this can take some time. When you see the 'CONNECTED' on your phone app, it (the DISHY) is connected & will be broadcasting a WiFi signal that can be seen by your Peplink device.
Initially, I would connect your Peplink device to the DISHY via WiFi. This is the simplest & most straight forward way to start. As a general rule one wants to minimize any variables when activating new 'stuff'. Once you have that accomplished, you can then proceed with Ethernet wiring. Your choice.
I have yet to do this as I'm getting pretty good performance via WiFi & I don't have any Ethernet cables readily available.
Based on what I've read, if you want to use Ethernet, you will need the Starlink Ethernet adapter, current firmware for your Peplink device, a switch between your Starlink router & Peplink router, necessary Ethernet cables & a change in the configuration on your Starlink router.
Out of curiosity, what motivated you to purchase a MAX Transit Duo? Based on your post, it appears you are only using one SIM with a device that utilizes 2 CAT 12 radios.
While I am not familiar with the Verizon Inseego, if it only has a USB port, I would suggest the most straightforward way is to use its WiFI signal to connect to the Peplink. See below for other options which might work.
Don't know who your Peplink partner is, the one I now deal with now has been most helpful in assisting me. He's only a phone call or email away. He even offered to send me an Ethernet cable for my setup as I've been to lazy to go over to offsite storage to get one. It's been my experience the lowest out of the door price for hardware is not always the least expensive if you need after the sale support. Have you contacted the entity where you purchased the device? The Peplink business model provides for them to provide 1st level support.
You might want to search this forum for 'Tips & Tricks' on how Verizon does or does not handle hot spot devices (I believe the Inseego is one of these) with an active data plan when you place that SIM in a Peplink device.
Hope this provides some help. Good luck!