Moving PostgreSQL servers to a new server

Hi,
I am new to PostgreSQL. My scenario is as follows:

https://cdn.bloghunch.com/uploads/uNxNoi5uVKeDibd5.webp

I have a Master server and two Replica (Replica-1 and Replica-2) servers. One of these Replica servers is in read-only mode and a report is prepared from it using Microsoft PowerBI. Due to a series of issues, I want to transfer the Master server and one of the Replica servers to other servers in two steps, but I don't want to have any interruptions.
A) Assuming PostgreSQL is installed on the new server, what should I do first to migrate the Master? Please show me a tutorial and share your experiences.

B) After transferring the Master, I want to transfer one of the Replica servers. What should I do to transfer this server?

Cheers.