I have a '26 R1S. The $300 Rivian CCS to NACS adapter is 0.03% (yes 3 one hundreds of a pecent) of the cost of my SUV. For piece of mind, get the real deal. Gemini told me the Rivian adapter is manufactured by Tesla. Consider the source. :)
I had the same experience as a new '26 R1S. I ordered the Rivian CCS to NACS adapter at $300. $75 ones on Amazon but thet all say they only work on Teslas. Not willing to experiment on my new Rivian. Until I got it just narrowed the charging networks to Tesla only to insure I could find a...