While there are technical challenges related to the sandbox, especially when dealing with different platforms (like Mac and Linux) the real challenge is having a good enough DX (for the app dev) and UX (for the app user) to allow/deny requests.
At the very least, an app should not be able to dial out willy nilly to a bunch of random domains. Also, it should be blocked from dialing out to local / private IPs unless explicitly allowed.
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