Felt a little lacking some research on options, and manifest configuration is quite a topic on its on, but otherwise an informative post about all the steps required to build an offline app in todays technology.

There are a few options for the frontend such as Angular/React or even webpack with other libraries to help with the offline caching, dealing with or programming service workers is pointless as they don't really provide any other benefit besides caching.

I ended up implementing a syncronization layer myself, which was challenging in a fun way, but I wouldn't use IndexedDB API, it feels much like WebGL interface: overly verbose, stateful, and the specification does not mind web developers at all. For those and other reasons I recommend [Dexie.js](https://dexie.org/) to handle the local DB.