The base currency on Bisq is Bitcoin (BTC). Bisq is a decentralized peer-to-peer cryptocurrency exchange that primarily uses Bitcoin as its base currency for several reasons:

Liquidity: Bitcoin is the most widely traded and recognized cryptocurrency, which means it has high liquidity. This makes it easier to find trading partners and execute trades on the platform.
Security: Bitcoin has a well-established blockchain and strong security features, making it a reliable base currency for trading.
Decentralization: Bisq is designed to be a decentralized exchange, and using Bitcoin as the base currency aligns with the decentralized ethos of the platform.
P2P Network: Bisq operates as a peer-to-peer network, and Bitcoin's robust network infrastructure supports secure and efficient transactions between users.

And concerning the mobile RPC wallet, updates is currently moving towards it and the public will be notified on our official website.

Read more on wiki:
https://bisq.wiki/