First design things to work fully offline. Full airgap between the system and the rest of the world. Then introduce features to update that airgapped system from one way data transfers (like sneakernetting a hard drive/USB/disk/tape). Then introduce additional features to get that data from a network but cached local. Then introduce networked features, and only if connecting to another independent system is absolutely needed.
Basically stick what has worked in tech and avoid developing SaaS. At least if you are making something for users and not shareholders.
First design things to work fully offline. Full airgap between the system and the rest of the world. Then introduce features to update that airgapped system from one way data transfers (like sneakernetting a hard drive/USB/disk/tape). Then introduce additional features to get that data from a network but cached local. Then introduce networked features, and only if connecting to another independent system is absolutely needed.
Basically stick what has worked in tech and avoid developing SaaS. At least if you are making something for users and not shareholders.