I'll be interested to see what conclusions you draw. I've been working on my own 5e Summoner, built off the 5.0 Warlock chassis, that is, the "split subclass" model where to some extent both Pact and Patron are partial subclasses.
I decided to go all in for the association with strange, esoteric stars and Forces From Beyond. Mine first contacts some other plane through an Astral Sign, which defines the form of your Visitant: the Sign of the Protean (hyper-morphic scout-/skillmonkey-leaning option), Sign of the Muses (support-focused helper option), or Sign of the Chimaera (Synthesist-style "fusion" option).
At 3rd level, your Visitant has developed its connection to the mortal world enough that you can bond with the ultra-distant planes where your Visitant comes from: Elemental, Celestial, or Umbral planes. Elemental is things like eldritch equivalents of genies, dragons, elementals, giants, that sort of thing. Celestial is the Biblically Accurate Angel option, but also any other form of theoretically-friendly but very bizarre entity. And Umbral is things like the Far Realm or the weird outer reaches of places like the Plane of Shadow, or even things like the WH40k Immaterium.