How to make Web Apps appear as First-Class Mac Desktop Citizens
Found a great way on Chrome Version 75.0.3770.100:  

1) go to the website you want to convert to an app

2) click on three dots / more tools / Create Shortcut + make sure to tick 'open in new window'

That's it - you now have an app that you can pin to your dock and you can cycle through them with cmd + tab. Awesome!