This is quite similar to what I was trying to explore with [1] & [2] yesterday.
Currently, the only option I found is to use localStorage and give the user the option to manually export and import.
Hyperclay has given me some ideas. What I want is something like [3] but that the user only needs to install once. One electron app that can load our mini-apps.
[1] - https://news.ycombinator.com/item?id=44930814