It's not the standard though so you can't rely on it
You totally can use RFC6979.
BIP340 even says how to do it: https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki#alternative-signing
It's not the standard though so you can't rely on it
I just added RFC6979 logic to my BIP340 implementation:
https://github.com/conduition/musig2/pulls/2
Seems reliable enough to me!
Woops, wrong link