Noting this code snippet from Laracasts by Korridor that I found really useful for mocking the Storage temporaryUrl for local development.

$fakeFilesystem = Storage::fake('somediskname');

$proxyMockedFakeFilesystem = Mockery::mock($fakeFilesystem);

$proxyMockedFakeFilesystem->shouldReceive('temporaryUrl')
    ->andReturn('<http://some-signed-url.test>');

Storage::set('somediskname', $proxyMockedFakeFilesystem);

He commented that:

Now Storage::disk('somediskname')->temporaryUrl('somefile.png', now()->addMinutes(20))

This returns http://some-signed-url.test and I can actually store files in the temporary filesystem that Storage::fake() provides without any further changes.