https://github.com/TeamNewPipe/NewPipe#description

NewPipe works by fetching the required data from the official API (e.g. PeerTube) of the service you’re using. If the official API is restricted (e.g. YouTube) for our purposes, or is proprietary, the app parses the website or uses an internal API instead. This means that you don’t need an account on any service to use NewPipe.

I see they are using peertube API. So do they web scrape?

Material files. Seems to do the job for me.