Number of users with Power BI Premium on premise

Hello, I would like to ask you an information, because I can't get a clear answer.
Let's say I have 5000 users and I want to deploy Power BI Report Server on premise, so I have to get Power BI Premium (no SQL Server Enterprise with SA available).
One single user is in charge of creating and sharing the reports (1 Power BI Pro licence) and the other 4999 need only to view the reports (which are filtered with RLS) frequently.
My question is: can I purchase the lowest tier Power BI Premium licence (1 P1 Node) since I'm using my personal server (e.g. 8 cores, 16 GB RAM)? Or do I have to get the number of nodes accordingly to my number of users?