A staking mobile wallet is unlikely to get used for staking for a number of reasons. The biggest reason is battery life. PoS is designed to distribute staking weight over time by creating two new inputs from each old input. With the splitting, though, the weight of each transaction goes down, making the wallet work harder after every cycle. Eventually, mining dominates battery usage and the user must shut down the wallet to save battery life.

In-wallet trading, however, is an awesome idea. I'll bring that up with the team. Suggestions on which exchange to support are welcome.