I think Publishers.Sequence is equal Observable.from.
Publishers.Sequence argument conform Sequence.
And Observable.from is the same
But Observable.of isn't the same.
public static func from<Sequence>(_ sequence: Sequence, scheduler: RxSwift.ImmediateSchedulerType = CurrentThreadScheduler.instance) -> RxSwift.Observable<Self.Element> where Sequence : Sequence, Self.Element == Sequence.Element
public static func of(_ elements: Self.Element..., scheduler: RxSwift.ImmediateSchedulerType = CurrentThreadScheduler.instance) -> RxSwift.Observable<Self.Element>