It's a Linux project that's replication what Little Snitch does on macOS - it doesn't decrypt TLS secured data but it does show and allow blocking of network connections (even if it can't see exactly what's going on inside this connections).
Combining eCapture features with OpenSnitch would be awesome. It'd be great if as well as tracking all network connection, you could flag connections sending specific data (like your name, email address, or phone number) to unexpected servers.
Because IMO, what my PC is doing and sending over the network at all times should be inspectable by me, on that computer.