Hi!
Here is the idea:
Implement the sending/receiving UI (especially on mobile) in a way that allows the user to specify their currency of choice (for pegging).
The transaction would of course still transfer sys, but the amount of sys could be derived from a price peg.

Alice can then easily send or receive 3.1415 $/€/£/ZEC/BTC/... worth of sys to/from Bob.
This would abstract the conversion rate and enable user friendly transactions.