Reading round the trans topic one thing I think we can say is it’s incredibly contested.
Do people who use email pronouns at work realise this? Have they done their research and then consciously decided to come down on one side and want to publicly announce this? And why this particular topic, you wouldn’t put Black Lives Matter in your email signature.
Personally I don’t think work is a place for getting involved in this debate at all, I have no interest in what gender any of my colleagues are/were/want to be and it has no bearing on how I’d treat them, so why do so many think this is a good idea?