Can I use "stuck" with a continuous form? In other words, shall I say about a parcel that has not arrived:
Hope it is not being stuck in the Christmas post
No, one would not typically use "stuck" in a continuous construction. Your example should be:
I hope it is not stuck in the Christmas post.
The only common continuous constructions are for referring to the state change from stuck to unstuck, such as "becoming stuck" or "getting stuck", or for referring to repeating events, such as "being stuck in traffic every day". However, when referring to a single occurrence, the continuous should no longer be used once the state has changed.
Similarly, one would only say "something is being destroyed" while the destruction is happening. Afterwards, you would say "it is destroyed."