For now it's mostly read-only. We have one component that lets you edit free-form text that syncs back to the sheet, called Notes. We also have a Comments component and a Chat tab, which don't sync to the sheet. And our big focus right now is to add more CRUD functionality.
Will be awesome to see more data collection functionality. I build apps like these for enterprise companies and this would fill a large gap for field worker type apps.
Hope you don't mind working at Google, or if you add excel/O365 support, Microsoft. Seems like a no brainer acquisition target for them!