When I have to use Safari, I use AdGuard, which has been surprisingly decent though less reliable than uBlock on Firefox. I believe that, for reasons unknown to me, it's allowed to install and use a local component outside the web browser, which significantly increases its capabilities. I was under the impression that WebExtensions was supposed to vastly reduce your security exposure from using extensions, but if anything in AdGuard's case it seems more intrusive.
Apple uses this model because they believe that an application on your computer that has been codesigned is more secure than a web extension that you could ostensibly install without Apple being in the loop. This is very clear if you look at how they've implemented their Web Extensions support in Safari 14.
