Not at all, you'd still be violating all the non-gpl licenses. Just because GPL is more restrictive doesn't mean it somehow supercedes all other licenses!

Not quite, there are far more aggressive licenses on repositories on GitHub, such as SSPL, which in theory by providing the SSPL licensed code, Co-Pilot should be open sourced under the same license to comply.

Except you're not allowed to relicense proprietary code you found on GitHub under GPL.