I think it’s worth it.
Just simply send a link along with that’s generally better and that lots of people are moving over. Watomatic could be looked into as a way to automatically remind people you are on signal when they go to Facebook you. It would then prompt then to install signal.
I take the attitude if they want to contact me either, phone, email or text.
Not possible
However as you are in the EU, Facebook have to add 3rd party support to whatsapp. So that people on whatsapp can still message users who are not on whatsapp. Later in the future, group support will be added.
No time frame of when it goes live.
https://www.theverge.com/2024/2/6/24063705/whatsapp-interoperability-plans-eu-dma/