How Do MTGTop8 / Tcdecks And Other Actually Get Their Decklists? (noob Here)

Hello guys,

I’m looking into building a small tournament/decklist aggregator (just a personal project, something easy looking), and I’m curious about the data sourcing behind the big sites like MTGTop8 or Tcdeck, Mtgdecks, Mtggoldfish and others.

I doubt these sites are manually updated by people typing in lists 24/7. So, can you help me to understand how them works?:

Where do these sites “pull” their lists from? Is there a an API for tournament results (besides the official MTGO ones), or is it 100% web scraping?

Does a public archive/database of historical decklists (from years ago) exist, or is everyone just sitting on their own proprietary?

Is there a standard way/format to programmatically receive updated decklists from smaller organizers?

If anyone has experience with MTG data engineering or knows of any open-source scrapers/repos any help is really appreciated.

thank you guys