Exercise 2: Can 500 Outside Testers Be Invited via a Public Link? — Possible Solution
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This is genuinely possible under TestFlight's own real tester
categories. The chapter's own reference table establishes that
external testers - which is exactly what 500 people outside the
development team are - can number up to 10,000, and can be invited
either individually by email or through a real public link with
optional enrollment criteria like device type and OS version. 500
testers is comfortably inside that real 10,000-tester ceiling, and a
public link is one of the two real, explicitly supported invitation
methods for external testers specifically.

The one real requirement that still applies, regardless of invitation
method, is Beta App Review: the very first build offered to this
external group must already be approved before any of the 500 testers
- however they were invited - can actually install it. Using a public
link instead of individual emails changes how testers join the group;
it does not change whether Beta App Review is required, since that
requirement is tied to the tester being external, not to how they were
invited.

ANSWER: Yes - 500 people is well within the real 10,000-tester limit
for external testers, and a public link is one of TestFlight's own two
real, explicitly supported invitation methods for exactly this
category of tester. Beta App Review is still required for the first
build these testers receive, regardless of whether they join via a
public link or an individual email invite.

WHY THIS WORKS AS AN ANSWER
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This correctly applies the real numeric limit and confirms the public
link as a genuinely supported method for external testers specifically,
while also correctly noting that switching invitation methods doesn't
remove the separate real Beta App Review requirement.