There seems to be a lot of confusion regarding Progressive Web Apps for regular users. Some people think the install prompt installs them from the Play Store, others assume they are Instant Apps (since a full application can't possibly be installed so quickly).
And of course some are disappointed when they find out they are actually build using web technologies (a.k.a. are not real apps).
https://www.reddit.com/r/Android/comments/7gromu/twitter_lite_in_the_google_play_store_in_24_more/