Can't deploy my back-end API from an Nx workspace to Google Cloud

Question

My Nx workspace looks like:

apps/  
    api-app     (nestjs + prisma)  
    admin-apps  (Angular)  
libs/  
    ts-common    (Typescript)  
node_modules/  
    all modules... (for all apps & libs)  
dist/  
package.json 

Now I only want to deploy the application api-app to GCloud.

I tried to place an app.yaml in the root: but then it uploads all app & libs and Then I tried to place the app.yaml inside my app (apps/api-app): doesn't work

Notes:

• This application is referencing another lib from inside the Nx workspace (libs/ts-common)
• This application has a project.json file (instead of a package.json)
• The node_modules are on the root level of the Nx workspace (instead of inside apps/api-app)

Does somebody has experience with this? Thx!