I discovered them because I am using Marp for all my presentations and they dropped their classical packaging in favor of this.
I also use Wavemaker & draw.io (diagrams.net)
I find quite useful to be able to install them in no time on any device and just to need a nextcloud to use them as a team.
I install them with Firefox’s SSB functionality and avoid chrome PWA method 
I don’t need to use any PWA, however it is an approach that I like more then using Electron
I’m quite fond of them and prefer them over the “native” store apps on my phones.
I also recently made one with Vue.js (personal use recipes app) and it’s certainly convenient to have the web application code magically turn into what feels like a native app when using your phone 
Do you have a tutorial on this ?
Not on the PWA part in particular, but here’s a little article I wrote summarizing the process. It’s full of helpful links too: Getting Started with Vue.js in 2020 - ttntm.me
I might get around to writing it up in more detail at some point but I don’t have enough time for that right now.