Need help with changing default footer text...

Hello,

Need help with changing the default footer text to my own brand name and links.

I'm not referring to changing it via customizer. I want my brand to show instead of generatepress. I don't care if the customer changes it via customizer to whatever they want. But of course if they delete whatever they've added to the copyright section it usually reverts back to "Built With Generatepress". I just want to re-brand it.

I'm confident I can change the core files to my own stuff but obviously it'll get erased once an update is pushed. I need something automated that I can add via child theme or mu-plugin.