Size of the file should have nothing to do with invalid character errors. I created some example documents totalling 1.4 GB with some emojis sprinkled in and was able to import them all without errors.
If you’re using jq, I’m guessing that jq messed up the emoji codes somehow. That, or the program you used to modify this file mangled the emojis. Could you try to convert your file as per @steevej 's suggestion (remove commas, remove the [ and ]) without using jq?
Best regards
Kevin