Is it possible to just have Othernet modem and and connect some kind of travel router to it?
That’s not how it works. While the “data” is exactly that - data - it is not routable and so a router of any sort will not be able to make use of it.
You could perhaps connect the DreamCatcher to the WiFi tht eminates from a router and then use the app from your laptop via that wifi. Not exactly what you are looking for I think?