In DnD you can have good aligned patrons - granted probably not as a fiend, though i always wanted to try out a walrock with basically Crowley from Good Omens (though Supernatural Crowley would probably work too) as a morally more amiguise fiend patron.
But there are good aligned fey patrons according to the lore, my feylock in our campaign has such a patron, some sort of water based nature protecting powerful creature. They actually have a good working relationship.
A friend of mine played a GOO warlock in a campaign and he had an agreement, that his character is benefitting from the powers and mostly left alone, but will go steadily more insane from the influence of his patron. I mean, what else to expect, if you have Cthulhu and his fellwow old ones as patrons.
I would have loved, if BG3 would give you some consequences - maybe make Raphael the patron of your fiendlock and in act 3 you have to decide, if you want to stay true to the pact or get the consequences. Ethel is probably not powerful enough to be a fey patron, but if her storyline would have been expanded, the feylocks patron could have gotten involved. GOO would have been a bit harder, but maybe with that, you would have starting to hear voices, make will saves or do erritcally insane things - if you ever played Vampire the Masqerade Bloodlines as a Malkavian - something like that, you hear and see things, that aren't there, maybe you get some insight, mabye your patron leads you to do some random stuff, you have no idea, why you are doing it, because you can't really understand the ways of an eldritch being.
It could be very unique experience for every warlock subclass, so granted, if Raphael would be your fiendlocks patron, you had more involvment with the direct story, though I can see the other two just being as fun. Ethels storyline is one of teh most popluar according to social media and a playstyle for a GOOlock could be very unique (again, maybe similar to the Malkavian from VtMB).
I'm a bit sad, that your warlock doesn't get to interact in any form with their patron or have a moral dilemma like Wyll about their pact tbh.
