HI Jose:
restaf is really intended to be used in your html javascript to handle rest calls to Viya - although it can also run on server. restaf understands the design of SAS REST API and thru a few methods users can deal with all the services in a similar manner. Additionally it handles all the data returned from the server for the user. I do not believe SAS has a one-to-one equivalent library in Python.

restaf assumes that you have a app server that serves up the pages- in your case it is a flask-based app server. So even if you use flask as your server you can still use restaf on the client.[Sidebar: If you are interested you can take a look at restaf-server - an opinionated app server designed for use with Viya].

However if your goal is to write the app in a python-only stack then either straightforward python or helper libraries like python-sasctl will be useful. I am not familiar with running python on the browser but I am sure there are ways to do that too.

Cheers...
Deva
PS: and do not forget the authentication flow in your web application - that is always a fun ride :-)