The problem CrossNftApp solves

Cross-chain communication means you can build a complete experience for your users that lets them interact with any asset, any application, on any chain with one click. CrossNftApp enables secure, any-to-any communication across blockchains, regardless of consensus mechanism or message payload. Cross-chain apps built on CrossNftApp are truly permissionless, meaning that their transactions cannot be censored by any oracle, relayer or validator. CrossNftApp is based on the same proof-of-stake security model as many of the chains it connects.

Challenges I ran into

Nft can be sent only to EVM based chains. We are looking forward to upgrade it to more chains
Since this uses axelar gmp it is little bit slow at the testnets