Per the link above, Safari supports x-webkit-deflate-frame. If you search for x-webkit-deflate-frame on Cowboy repository, you will see it explicitly checks for this header, alongside permessage-deflate.
Compression happens within the VM by calling zlib:gzip/1, which is a C binding to zlib, the lib used by most systems and apparently Nginx too. I actually like that compression is handled in Elixir because the data is compressed from beginning to end.
First things first: Happy new year!
Thanks to all participants for the awesome questions and answers to clarify what the differences and similarities of the systems are.
I think, subsuming the thread, that the systems are different enough to justify salvaging some ideas from over there 
In the end this is what this thread seems to be about: Someone interested in a "Basecamp Hotwire" library for Phoenix? - #11 by cnck1387 so I won’t recap in here.
Lastly I’d like to take a moment to acknowledge how utterly awesome this community is… I mean really: I just posted a slightly tounge in cheek comment right before heading into the holidays and it ensues the most productive and civil discussion you could imagine - even with deep participation of the creators of the mentioned technology. This is incredible…
Despite all the technical bells and whistles of the platform: the community around Elixir is, for me, by far the biggest asset and best feature of the whole stack. Thank you all so much 
OT
Is there a branch for this? I’d like to help with this if possible, since I have a usecase for this 