Deploying GC App Engine Standard

Hello,

I'm currently deploying my Laravel app to Google Cloud App Engine.

I followed the Flexible and Standard deploiement tutorial from Google Cloud Community :

• https://cloud.google.com/community/tutorials/run-laravel-on-appengine-standard
• https://cloud.google.com/community/tutorials/run-laravel-on-appengine-flexible

And I succeeded on deploying it in Flexible mode (working perfectly) but I can't figure out how on Standard mode as I don't have access to the public folder once I deployed it, so my website doesn't have any ressources (CSS, images, videos, ...).

Here is my app.yaml for flex which is deployed and running : https://pastebin.com/5bGswhxR

What should I replace to pass from Flex to Standard ?

Thank you in advance for any help