It’s amazing how, oftentimes, regional cuisines are differentiated by minute, little things. In Ipoh, one of their most popular street food is simply called “Nga Choy Kai”, literally “Beansprouts Chicken”. Their poached chicken is of Cantonese origin - which is still quite similar to Hainanese poached chicken.
The main difference, I’d say, is that the Cantonese serve their chicken alongside plain, steamed white rice, instead of the Hainanese-style, where the rice is flavored with chicken drippings, ginger and scallions, and cooked with chicken stock. But here, in Ipoh, Lou Wong and its main competitors like Onn Kee, will serve chicken-flavored rice as well - though they’d insist theirs aren’t “Hainanese-style”.