There’s already a tool for macOS called “Little Snitch”, and it has been around for years. It is an outbound firewall and lets you look at stuff like this.
IIRC, there’s another outbound firewall called LuLu that does the same sort of thing.
Will be giving this a go. I'm currently looking at both DNS and IP/Network blocking, and this will be a useful tool as part of that journey.
Is this only for Mac? Or can I use windows or linux as well?