:focus-visible is still behind an experimental flag, but once it's shipped we could probably want to add the possibility to force it from the Web Inspector.
<rdar://problem/75255503>
Now that :focus-visible has been enabled by default in Safari Technology Preview 138, maybe we want to fix this issue. See #222644 which is related to :focus-within, that is not yet possible to force in the inspector.
*** This bug has been marked as a duplicate of bug 241655 ***