Rather than getting into an analysis of the characters relative to their respective archetypes (the repetitive time loop = Nemesis, everybody else = Trickster), I want to focus on Nyles and Sarah. For in my view, the biggest reason this movie works - as distinct from other repeating time loop stories - and why it sold for $22M at Sundance in 2020, is these two characters.
It's not like Nyles is a remarkably different character. Indeed, he feels like a first cousin to Phil in Groundhog Day. Cocky, smarmy, ego-driven. These two characters are cut from the same cloth.
What's different - as I noted previously - is that it's not just one character experiencing the time loop, it's TWO: Nyles AND Sarah. And that creates a whole different narrative dynamic.
In Groundhog Day, Rita has ZERO AWARENESS that Phil is reliving his days. Thus, even though it works - Phil falling in love and having to prove that he can be selfess, as opposed to selfless, with his "perfect" day to "earn" Rita's love (as far as the audience is concerned) - there is a way in which it feels contrived. There's no reciprocity, it's all about Phil changing in order to fit with Rita's expectations of a lover.
That problem, if you will, is addressed full-on in Palm Springs
When Sarah gets thrust into the repetivie time loop, Nyles is already way down the road with it. He's rather cynical about the whole thing, lost in an endless cycle of doing whatever he wants to do, falling asleep or dying, then waking up just as he was at the start of the day.
When Sarah experiences it for the first time, she has a lot of catching up to do. For much of the story them, the two are at sixes and sevens. He's cynical and knows it all. She's in denial and can't believe it's true. He has fun showing her the ropes. She is angry and tries to break free. At some point, she shifts into his territory of acceptance and begins to have fun with their shared reality. And there's a period of time in Act Two where the fact he's able to live these time loops with Sarah starts to change Nyles. He's falling in love with her, even if he doesn't quite know that yet. Meanwhile, Sarah goes into "let's kick out the jams" mode. She's become like Nyles was at the beginning of the story, only he has changed. So again, sixes and sevens.
Eventually, she falls in love with Nyles and they both match up emotionally, but here's a key: What Nyles sees in Sarah - her cynicism, her embrace of doing stupid shit because, "Hey, why not, we're just gonna wake up same time, same situation tomorrow" - is a reflection of who he had becomes. And he doesn't like it. He's having GENUINE FEELINGS for Sarah and there's a critical period where she is NOT at that point... and Nyles feels a sense of loss.
Fortunately, they do connect. And Sarah comes up with the plan to escape (this is a critical story choice, as this gives her character the key to resolving the central problem), and they end up together, freed from the loop.
The point is this: It's not just about Nyles doing everything. Indeed, at some point, he is helpless, caught up in a hope that Sarah will eventually "see the light." Indeed, the second half of Act Two is more about Sarah getting her act together than Nyles. Thus, in contrast to Groundhog Day, this story has more balance between the romantic partners. Sarah is the anti-Rita, not just a love object, but a Protagonist figure in her own right with her own sense of agency.
Which is not to say Palm Springs is better than Groundhog Day. They both work. Rather, it's a testament to how Palm Springs traffics in narrative territory which Groundhog Day did not explore.
And it's all about the two central characters: Nyles and Sarah.
