If you added the capacity to buy and sell BTC/XCP 'NFT' asssets - this would be huge, and a unique proposition others don't have (having these historical OG items seems like great point of differentiation to again show Enjin is the leading NFT wallet/market place).
These assets are on the BTC chain itself (which is what they are set/received on) - so ofc Enjin wallet already supports this. You would just need to enable these assets to be visible / tradeable.
The current place these are aboe to be traded has some very challenging UI - so by adding it to Enjin marketplace you would suddenly access an OG community and give access/liquidit to these assets.
Here are some useful links:
https://counterparty.io/ - the platform used for these assets presently.
https://freewallet.io/ - one of the main wallets used for these assets.
https://play.google.com/store/apps/details?id=com.everdreamsoft.casatookan&hl=en - this is a wallet (not so well known) that accepts both ETH and BTC 'NFT' assets.
In telegram, this is a dev that could assist you with any tech info you might seek.