How to expose branch preview URL to public domain (branch.myapp.pages.dev -> branch.myapp.com)

Hi folks, I have a staging branch that is is routed to the branch preview URL like this

staging.myapp.com -> staging.myapp.pages.dev

staging.myapp.com -> staging.myapp.pages.dev

staging.myapp.com -> staging.myapp.pages.dev

staging.myapp.com -> staging.myapp.pages.dev. How would you do the same for all preview branch urls? I'm looking for something like this:

[branchname].myapp.com -> [branchname].myapp.pages.dev

[branchname].myapp.com -> [branchname].myapp.pages.dev

[branchname].myapp.com -> [branchname].myapp.pages.dev

[branchname].myapp.com -> [branchname].myapp.pages.dev.