Nostr? Sure. Damus... maybe not sadly unless you find a way to install it with a jailbreak I guess
Discussion
If I was in HKG and I was using Nostr using Damus, would it be possible for me to transfer my identity and content to another app?
Totally. Your key pairs(npub and nsec) are not tight to any client (Damus for example) you could use them in any other webapp like snort.social, iris.to... etc or any other app. So, your profile setting, posts, followers, etc... Will be there as long as you have the nsec (private key pair).