Oh nice! The developers of Little Snitch have made a version for Linux. Like they say at the start of the post, I never found an alternative I was happy with when I switched from macOS to Linux. Although, with vastly more open-source software in my workflow it was also less necessary.

https://obdev.at/blog/little-snitch-for-linux/

#Linux

Little Snitch for Linux — Because Nothing Else Came Close

Recent political events have pushed governments and organizations to seriously question their dependence on foreign-controlled software. The core issue is simple and uncomfortable: through automatic updates, a vendor can run any code, with any…

Objective Development
@wezm OpenSnitch has been around for a while. How does LittleSnitch compare?
@glitch Can't say. I haven't been able to run this LittleSnitch yet, and my macOS experience with it was nearly 10 years ago now. I also tried OpenSnitch many years ago, but it didn't stick. I don't recall why.