XRP to Xah To something else

So this is more a general question, in simple terms i am building an app that takes one transaction and lets say splits it into 3, a little bit like the carbon off set - so i have a smart contract on the xahau network.

Now anyone with an xahau wallet can use the app to pay for stuff.

First point of clarity would be ....

I am a new user and i have to ...

Download xahau wallet
2. Create my acount
3. Add some money onto my account
4. Purchase xrp to activate my account

At this point as the app needs to call the smart contract on xah network, all transaction will have to be made in xah ?

ie i cant then send xrp to the smart contract for the transaction (this confusion has arisen as i have been using hooks builder and the UI says transaction is in xrp but the transaction is in xah)

If the answer is yes to all transaction have to be in xah then that would mean that the reciver of the funds would have to move his xah to the xrpl, trade to another coin then off ramp to fiat.