Nuki Opener support for Elcom REK621Y

That’s actually sad. Ring-to-open is the feature I like to have implemented with the opener, as I’m already able to open with switchbot

Would it make sense to hire a professional to solve this mystery or can it also be impossible with the nuki opener for Elcom REK621Y?

You are right about the RED114Y, but you can also receive the ring signal. Since the RED114Y can only be programmed for one function and you actually need two functions, you need another RED 114Y relay that recognises the ring signal and sends the opening signal to the Nuke Opener. By the way, I was not able to do this myself, but my electrician did it successfully as described.