How to store a file with a certificate for digitally signing a program?

Question

Digital certificates

I'm completely green in the question.
Here, I generated a sert.p12 file for a digital signature. It is used during assembly.
Is it ok to add it to the public repository? It's safe? Or does it need to be stored somewhere in a closed place?
On the local machine, I can put this file anywhere, but the build is done using GitHub actions.
And I want to make the same certificate for Windows in *.pfx format. How are things with him?