I use silent link esim with GrapheneOS. Pay with XMR. Fantastic for privacy.

I am interested to know- if I have phone with local sim and using another phone on wifi and all apps of communication ect like Signal is in second phone, what telephone provider sees? Can provider track the data of communication in second phone ? Like with whom I am communicating? second phone would have GOS.

You can't pay for privacy. Anyone selling you something and advertising it as private are just grifting. The most private software is libre-software which tends to be monetarily free, but the private quality comes from the user's behavior not the software itself. There's no program or thing you can buy or use that becomes a "privacy blanket" and magically makes you private. It doesn't exist.

You seem to lack a technical foundation from which you can base decisions of. Read some books about computer-networks. If you're not interested in that... then you're not interested in privacy within computer-networks.