Although the character is never definitively identified, Joyce's rock star boyfriend Graham is most-likely supposed to be Graham Nash. Clues are that he is part of the folk rock scene (associated with the real life musicians identified in It's Okay to Like It (2023)), he has a British accent, there are four male subjects of his photo shoot i.e. Crosby Stills Nash & Young, and one of his associates is named Neil, i.e. Neil Young.
The groupies that Joyce speaks to are named Sable and Bebe, who are probably supposed to be famous 1970s groupies Sabel Starr and Bebe Buell.
The name of the lead male character in Shelly's story is Gian-Paul. The name most-likely is taken from Gian-Paul Bergeron who is the writers' assistant for this show.