Don't bother using Little Snitch. It's mainly used by those pirating software that wants to stop the pirated program from connecting to the activation server for said program. It was like this in the past and I doubt it has changed. Security might have a thing to say here. Or Nagcurity.
With that said - I've used it after some 3rd party apps getting more and more in the zone about sending data off of my Mac to their servers and diagnostics department. I dislike that trend. Am I going to hunt every checkbox in every app to tick that off so that no data is sent? No. Little Snitch can give you a heads up on those particular apps. But it's just not worth it having to spend most of your adult lift deciding to allow or deny a connection of which there are so many.
I also tried the Hands Off! app and the ones from
https://objective-see.com/products.html - none of which does anything for me. Objective-See does have good apps that hooks onto the OS - but I would rather enjoy my time with my Mac and macOS than waiting for that popup of allow or deny. I want Apple to let their OS send off diagnostics - but if I don't I find that spor in the System Preferences and turn it off.
I wouldn't bother installing Little Snitch. But these days security is in the high seat. Can you avoid any attack from the Internet with Little Snitch? Possibly. It's the approach to the interface of Little Snitch I dislike the most. The never ending growing list of apps and services piling up in the Little Snitch Configuration. The newer Little Snitch 4 looks rather nice interface-wise. Some new things that might get me more inclined to use this app in the future. Basically I'm all over the place with opinions and have no clear agenda other than to perhaps dive in and experience Little Snitch yourself.
Before someone comes in and says "But what about ransomeware" Yes that is a problem. Little Snitch can help you not get ransomware? I try to not think too hard because of my dislike for thinking too hard about potential threats.