Re UK
It is not easy to say, but younger people are more likely to adopt this language.
As English has neuters, and not just masc and fem, some things are easier. French and Spanish I know are debating many things.
Chairperson was fairly widespread but I think it has largely been replaced with the simple ‘chair’. In business and politics I’d say almost complete adoption of this phrase, or say that X chaired the meeting.
Actor. I still say actress as in particular during the #meetoo movement in particular I thought it was clearer. But I will continue to use it, as I find it better.
However most of the -ess suffixes have gone. I haven’t heard murderess or manageress for decades now. I am not sure about school governesses, but I think so. Possibly say one of the school governors instead.
Police no longer have WPC or WDC for Women Police Constables or Women Detective constables since at least the 90s.
I would say increasingly common, certainly compared to 20 years ago