To throw in my slightly late tuppence worth. I'm an IT manager and work from (floating) home once a week, plus being a gamer geek have various streaming services inc 4k video.
I bought a TCL LinkHub which has 4 & 5G capability, paired this with a sim only vodaphone deal which has unlimited data plus uncapped speed. I'm moored in a 4G only spot at the moment and speed tests are 100-150Mbps on WiFi and 250-350Mbps for hardwired devices.
The router is inside the boat, not in a window and doesn't have an external aerial. It is bigger than the little dongles but has a couple of ethernet ports, does 2.4 and 5Ghz wifi bands and will support way more connections than i'll ever need.