Several years ago I was asked for a software for inhouse maintenance technicians (for AC).

As some of the customers were in the middle of nowhere, the technicians would have to check boxes on their checklists without the possibility to validate it online.

We add to go for a native app as service workers were not a thing at the time, but it would have save us a lot of time if we could have use plain html/js

I was working on an internal inventory tracking system a few months ago, and three weeks before delivery the product team discovered that the rooms where the back stock is counted have no wifi signal. I was able to make it work offline with a service worker in three days without major changes to the architecture.

Entertainment sites like blogs or image boards, todo apps, note taking apps, recipe websites etc.

Basically PWAs allow you to build features that were only possible in native apps before.