I have an old Huawei router that runs off USB using a cable to convert the 5v to 12v. My aerial is the Poynting 4g XPOL. The router came free with a Three contract a few years ago. It's currently got an O2 sim which is part of our Virgin Media package.
If I was starting g now, I'd get a 5g router, which seem to be around £250 and a Poynting 5g XPOL antenna for around £90.
I can't see what the Maxview could do better, apart from connect to ordinary WiFi, so it seems like an expensive solution to buying a router and external aerial.
Having said that, I don't see how it would be better or worse on a boat..... it does the same job on both boats and RVs.