Well, SN's PWA, browser-generated SN PWA and browser all keep open separately. So, I think my Bromite does seems to generate PWAs if that's the case. It's a derivative of Chromium but has 'enhanced privacy'.

This thread has helped a lot. I'll try and utilize PWAs more now.

Thanks for your link - looks good too. I'm going to download it via github and check it out now.

Edit: message: "I couldn't find a suitable release"