But going ahead after deleting it, facebook shouldn't be able to gather more data about you or will they? I'm deleting everything by tomorrow evening and figuring out what search engine to use as I know using Google Chrome isn't a good option and neither is any Microsoft or amazon platforms.
Yes, they can (and do) still gather data about you - even if you don't use FB.
Every site that has an FB icon tracks your IP address, and FB knows you've been there - think every online shopping store, every hunting and outdoor goods site that has a 'Find us on FB' button, and so on. So if you purchase items from shops that use FB (which is almost all of them), the fact you visit their sites will be tracked by FB - even if you don't click on any FB buttons on those stores' stites, and even if you don't look at their FB pages.
And that's only the sites you can see ... many companies place third party cookies on completely unrelated sites - news sites, discussion boards, and more. You don't know the cookie is there, and you don't give consent to have your info sent to a third party. But the companies can then track your visits to multiple sites. From about 2012 to 2019, Mozilla had an extension (first called Collusion, then Lightbeam; both now not supported) that allowed you to see the large network of sites that tracked your browsing across the web ... it was downright scary.