Squee says, “When this creature is destroyed, return it to the battlefield with its reinforcements.” When you destroy it with Gather the Pack or Growing Rites of Itlimoc, Squee is not returned to the battlefield.
Squee not returned to the battlefield when destroyed by Gather the Pack and Growing Rites of Itlimoc
I think the discard effect isn’t considered as a card destruction. However, the cards go to the graveyard and can be fetched or played from it as any other destroyed card.
In other words, they dont get destroyed as a process but they get the destroyed status as a result.
I believe the general rule in paper MTG is that card abilities are only active on the battlefield unless the card says otherwise. This game isn’t as good at stating clearly which abilities activate in other zones, but it does seem to follow that rule in general.