As can the (FOSS) LuLu: https://github.com/objective-see/LuLu

that works in a lot of cases, but unfortunately it seems sometimes you get these popups about nsurlsessiond (for example) where you know where the connection goes, but no idea where it comes from (especially if it's trying to connect to to some generic AWS hostname)

And as much as you can use little snitch for programs you install, these days it seems an endless whack-a-mole to block Apple's stuff as there's so many requests all the time. The more time goes by, the more it seems that the concept of "personal" computer is gone: there's nothing "personal" about it anymore, it's the computer plus an amorphous blob of online services one has no control over.

Some Apple Apps can bypass Little Snitch though.

https://news.ycombinator.com/item?id=24838816