Very interesting. I can fairly reliably whistle a middle-c but I find it hard to take it from there (other than just the scale in the key of 'C') and picking out absolute pitches by ear is not something that I think I can do reliably. But I did get that tune right on the first try (probably just luck).

I've been doing a ton of relative pitch ear training in the last couple of months and I'm slowly getting better at it but this is very hard work once you get past say P5 and harmonic I find much, much harder than melodic.

edit: nice app from that last link: https://www.musictheory.net/exercises/ear-note