Not much impact for a single vehicle, but if somehow magically deployed at a mass scale 10 days of travel a year erased from even just half of our shipping truck Fleet would be a significant boon.
Let's not forget the panels don't only work when the truck is in motion, there are lots of trailers that just sit in the yard for good chunks of the year. They can now be plugged in and feeding the grid during that time
I would recommend reviews, and honestly just make a really good product. An advertisement for a product is usually my red flag to avoid it I try to find products that speak based on their quality. If you do go for something like a YouTube review make sure it's with a YouTuber that has a clear stance on not letting reviewers control the message because that gives users significantly more confidence in that review. Which means that they are more likely to purchase that item
For the type of needs that you have I would recommend that you separate your connectivity from your routing. As in find the best quality LTE router you can for the signal and then simply have it pass the connection through to a dedicated router. I would recommend a nice micro ITX router box with opnsense, you will never have to worry about it not getting updates and it will be able to easily handle your many multiple Network needs.
https://www.amazon.com/dp/B09LNLMH9Y?
This box would be a bit overkill since it supports 2.5G but i have this unit and can recommend it. It would easily be able to handle your desire to have so many separated networks some with vpns some with not. and you could easily tie each network configuration to a different output port allowing you to have them all running simultaneously if needed