I don't think that exist as such, very few cameras that take a sim card, but some wifi enabled cameras some with smart features like cloud stuff.
But it is going to cost ya, a dashcam if you want to transmit its raw 1080p footage generate about 100 megabytes every minute, so for 10 minutes of driving your data plan take a 1 gigabyte hit.
And also you better be having darn good 4G coverage or you will be really "lost" as you cant cram that much data thru a flaky connection.
Even in pretty well equipped and flat Denmark you will not have to work all that hard to be in a place with just 2G coverage, and we even have small total dark spots, though new law mandate that all Danes must have at least 100 mbit one way or the other, and two 5G networks going up in this small country.
