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
I hate when people put stories like this out in the form of 15,000 tweets. It’s a pain in the ass to read, just link to a paste bin or blog site or literally anything where I can read it in proper formatting and not broken out into a million tiny pieces