How to validate api call with okta service in flask api which is acting as backend

I am building an app with mvc model. Vue is my frontend framework and flask is backend framwork for API which is connected to DB.
I can authenticate user on frontend through okta and provide access to application frontend. Now I am trying to implement okta on backend flask api to validate the API call and authorize CRUD operations.
I am using Tutorial from okta but it is using web application on okta, I am using single page app and i dont have “client_secret” and also i dont understand what is

app.config["SECRET_KEY"] = "{{ LONG_RANDOM_STRING }}"

Can you please help me on how to validate api calls on backend flask be process request ?

I am ready to share my work either frontend vue code or backend flask code.

It sounds like your Flask app is acting as a resource server. I believe the tutorial you are following it is acting as we web app that you login to. Since you have the Angular FE portion working I would suggest looking at one of our Python samples using Flask as a resource server.

After following the steps and using the code for oidc, i get error
{“error”: “invalid_token”, “error_description”: “Token required but invalid”}

And dont know what is “client_secret”, I am using single page app.

That tutorial won’t work with a Single Page App. Try creating a Web app in Okta, that should provide you with a client id and a client secret.

Is there any chance to get single page server side authentication document or support ?