You have read like 600 articles on SEO and you still aren’t sure what it is, but that’s fine. Everyone keeps telling you to “make sure you use keywords” and “make sure you do updated keyword research” but you don’t even know what that means. In short, the “algorithm” (aka the tech that determines what to show you) on social apps AND Google both work similarly in that you will be connected with other people who have stuff in common with you.