Yes, it is, with one exception. Just like any other card, your cards from Collections can be traded. Once you list the card for trade, it will disappear from Collections and will be added back only when you remove it from the Marketplace.

The exception to this is when cards are a part of a completed set. In other words - once you claim the reward for completing the set, cards from that set cannot be traded nor moved from the Collection. This restriction will be removed on September 6, 2023 at 23:59 UTC and after that all the actions will be possible again.