Unity has async too [1]. It's just that in a rare display of sanity they chose to not deprecate the IEnumerator stuff.

[1] https://docs.unity3d.com/6000.3/Documentation/ScriptReferenc...

Oh I totally missed this, thanks! I was overly confident they wouldn't have bothered, given how long it was taking. The last time I used Unity was 2022.3, which was apparently the last version without Awaitable.