Flow authorization code with PKCE dependencies

if authorization code with pkce is used, what is the function of this dependency apart from generating the code_challenge and code_verifier ???
to handle the url is also required or other characteristic?
apart from the okta SDK and the widget to use these tools is the crypto web required ???

thank you

Here is the article of Okta PKCE flow. Not sure if you read it before.
There is another good reference in the link.