Parts availability for a new and/or low volume vehicle is always tough whether it's an EV or otherwise.

But process of replacing a radiator on a Rivian really isn't any different than replacing one on a Jeep.

Most people who work on any vehicle don't know what the fuck they're doing, there's plenty of people in Autozone buying their 3rd O2 sensor for their Jeep that's throwing a P0420 as well.

That sounds like a you problem.