Weapons...as the article I've attached notes, those states that have used CWs in the modern age (e.g. Rhodesia and Syria), have done so "In Extremis" when fighting against insurgents threatening their regime's existence...don't see that scenario existing for Russia...yet, it's possible that Putin is "All-In" on his "Mission" and will never leave w/o getting his "pound of flesh" out of Ukraine, through any means necessary...including CWs...
I've mentioned elsewhere that I see Biden's "In Kind" remark as alluding to actions (but not CWs) that would have as much impact or more impact on Russia as their use of CWs...not sure what that might be...but he and our military are obviously discussing the options....but, I don't imagine Biden would authorize them in Ukraine...and, short of an "In Extremis" situation here at home, I don't see us supporting their use anywhere.
Hopefully, we can use our knowledge of CWs...and 'remedies'...to prepare Ukraine for any possible use by Russia...but again, I don't envision us going 'tit-for-tat' and expanding the scope of the conflict...
Sadly, this question isn't going away any time soon (see article)...lots more to learn...not just about CWs, but also ways we can build international agreements and working relationships that make it nonsensical to employ CWs...a bit 'pollyanna-ish', but hey, worth holding that thought.
Link: https://warontherocks.com/2017/08/long-ignored-the-use-of-chemical-and-biological-weapons-against-insurgents/