Yes Sir, I think it's teachable.
Actually yung teacher namin nung nagpaturo kami ng tennis dati ay seriosly mas quick pa ang service motion kay Dolpogolov...and very effective sa club level.
At dahil ganun serve nya ay yun ang tinuro nya samin.

Pero wlang gumaya.. Hindi maporma eh.

Iba parin yung matagal ang trophy pose ala Sampras

It looks unorthodox, pero tama si Sir Lito na katulad din sya ng service motion ng ibang pro.
The biggest difference is in the toss. The lower your toss is, the quicker your racket needs to get to the contact point. And that what he is doing.
Yes, it's a little bit harder to execute because your timing needs to be great.