I don’t use a thumb pick either and I usually do straight natural harmonics using the fingernail on my index or middle finger. But to do these harp harmonics, unless you have a thumb nail that sticks out like a sore thumb, you are going to need a thumb pick. The thumb pick also moves the picking location back about a quarter of an inch (which up there is about a half a fret) so you don’t choke the note.
I hope to learn how to do this stuff someday. I guess you just have to practice it over and over until you can do it in your sleep.
When I first started finger picking after playing with a pick (mostly electric) for many years I thought it was really, really hard but, I kept it up and now I do it subconsciously. (and pretty darn good) That is probably pretty much what you mean by “doing it in your sleep”.
I never really got serious on acoustic until about three years ago.
I am interested in learning about posting online videos. I suppose it’s googable. Talking about playing on the internet falls way short of showing and sharing.
Thanks for posting this.