Finnian,
It's not possible Offline Survey123 data is not available for use in other Esri apps.
This may be an Idea to enter into the system.
Basically, it sounds like you want an offline map that shows previous survey data, that is accessible to users while conducting a new Survey. You could create an offline Explorer map (MMPK) that contains the previous survey data, your user(s) could download the map prior to going into the field. While the new survey data will not show up on the Explorer map, people in the field could switch between the apps to see previous survey results.
Mark