Secured request between two applications of the same domain

Hello!
I have a auth0 domain where I have two applications using auth0 to login:
• a nextJS project
• a reactnative application

What I want to do seems “simple”: I want the reactnative app to send fetch request to the NextJS API to retrieve some data. To secure this request, I want to use auth0 to be sure that the request come from a valid user session.

I tried a lot of things and for the moment nothing worked:
• put the accessToken as a authorization bearer on the header and using the
withApiAuthRequired on my NextJS route (like here)
• followed this guide but with no success.
• others stuff with no success…

Is there a good way to achieve what I want?

Thank you!