I've started building out an api for a vue front end and I've just been using standard api routes in Laravel and consuming them using axios requests from VueJs.
As I intend to serve mine as a subscription service I'll likely be wrapping it into Laravel spark https://spark.laravel.com/
Getting understand the fundamentals of how to build an api, and how to test it using postman has been an essential step to my journey. As has this book https://apisyouwonthate.com/
Start small and rebuild often to help you build out your specification. Its best to start simple as its easier to make things more complex when you have got more details.