Working with backend and frontend

How can one connect his/her backend in project idx?
I am using different templates. I am using Laravel for API and flutter as my frontend.I have used public ports to test my Laravel Api’s (I appreciate that the team added the public ports) but I am stuck in connecting the two. I have tried going through the full stack blog but I haven’t understood it. Can one kindly explain to me how I can make a connection between the two?

Have you considered editing .idx/dev.nix file ? in this way?
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