Yes, i'm one week in on my Rivian and i now am starting to "get" charging. definitely get a Level 2 charger of in your garage. But to the initial question, yes, your Travel Charger will work, you just need a 240V receptical.
The higher the amperage the better of course, but even a 30A, 240V would do fairly nicely unless you expect to do back to back long-haul driving. For me personally, my long hauls are usually weekends away so coming home on a Monday i would have more than the normal 10 hour evening charge timeslot.
And then in a pinch, EVGO is starting to build out quite a few fast chargers in shopping malls, etc. They are VERY expensive to use however, so careful on that. And be sure to not make the same mistake i did...get their basic $4.99 package, otherwise you'll pay a $5 "session fee"...which i did when i was trying it out for the first time.