The nextjs one uses a third party (bigcommerce) as the back end. Firebase is also a third party backend. Any recommendations on one where you can own the back

The nextjs one uses a third party (bigcommerce) as the back end. Firebase is also a third party backend. Any recommendations on one where you can own the backend yourself, like Django? Without composing all the pieces manually? I'm currently running a Django backend, Vue frontend, and think Django is a fine tool -- but occasionally look for a nice cohesive Django alternative in the JS world.