Two weeks ago, I posted a blog (and podcast) about my customization within Little Snitch which eliminates much of macOS's telemetry. Since then, my computer has had time to alert me to new process connection attempts which has extended my settings considerably. The following image displays a partial view of my current settings, which do not appear to break any vital macOS functions. Note that I added a few key privacy apps in order to display some optimal settings.
As an example, notice that Signal is allowed to connect to its own servers, but all else is blocked. This prevents URLs from being fetched when typed within a message. Linphone is allowed to connect to my VOIP providers, but not allowed to send any data to their own servers. KnockKnock is allowed to query VirusTotal, but not send any telemetry back to the provider. All Microsoft, Adobe, and VLC connections are blocked.