Red flags might not actually matter in many use cases. But where it does, setting up a decoy OS that boots on the computer by default when turned on may be one good strategy.

For a VeraCrypt volume, setting up an outer volume with convincing files and providing the decoy password may be effective.

Whether the mere possession of a Tails USB adversely affects your situation is a matter that remains to be discussed at length. There is clearly no one situation that applies to everyone.

HiddenVM's potential to provide deniability is about cryptographic deniability, not human deniability. Software can only do so much. If humans are suspicious, software alone cannot change their minds.