About half of them are skippable.

Hold on to Your Web Shooters - none

Parting Gift - Meeting Ganke in the park

New Thwip - Holo-Pete glitching during the training sim

We're Here For You - AFTER Simon Krieger's commercial, checking the terminal, checking the Nuform map

La Nochebuena - Opening the door for Phin, sneaking back into the apartment through the window after powering the transformer, eating dinner (these two are back-to-back)

Harlem Trains - First meeting with Unc, removing signal jammer, getting the Subway pass from Unc

Reconnecting - Meeting Phin on rooftop, opening locked case, Phin holding locked case (these three are back-to-back-to-back)

Time to Rally - Beginning of the rally (after running from Miles' house), landing between Roxxon and Underground on the bridge, saving the woman falling from the bridge

Someone Left the Lights On - none

Corporate Espionage - initial cinematic arriving at location, when Prowler arrives, observing Krieger from above while in vents, after picking up phone, Prowler's reappearance (appears from invisibility)

Underground Undercover - after texting with Ganke

Curtain Call - examining the reactor in the theater, reactor after the 4 generators

Breaking Through the Noise - none

Tinker Tailor Spider Spy - after getting murked by Rhino, pushing double-doors aside and open, doors sliding open before the Rhino fight, Ganke helping Miles through the door

Thicker Than Blood - none

Like Real Scientists - going through the glass doors before the flashback, the wipe into the flashback (these two are back-to-back)

The Battle For Harlem - leaping in at Phin by a nuform reactor (this is AFTER an unskippable cutscene), Phin falling down a building (these two are back-to-back), after phase 1 of Phin fight, Roxxon tower blowing up, cinematic introducing phase 2 (back-to-back-to-back), after phase 2 of Phin fight, after phase 3, cinematic after phase 4 (before crawling to the nuform reactor) is NOT skippable

I also noticed at least one instance of reloading checkpoint skipping an otherwise unskippable cinematic (the intro to Like Real Scientists). I'll do some more testing with that.