My past experience….
Super tiny eye dropper from vet as infant. When a bit larger when crawling, the milk soaked cotton ball helped to transfer to drinking from a bowl.
Have a foster mother that is nursing.
It’s hard before the hairless ones are two weeks old. One week old is a struggle. One day old is very hard even more so if you have to keep tabs on which baby is who and you are fostering five or more. I actually had two dwarfs that would nurse any baby rodent of even a teddy bear hamster and mouse for about 3 weeks max because I was worried the foster mom dwarf might hurt or get hurt by the babies after they could eat hard food and obviously looked different.
Strange Accident.
One of my dwarfs CowRu who fostered babies to nurse refused to let me remove a 4 week old mouse from the nest though, she’d let me pick up all the other babies and would still nurse them.. just that one mouse she kept.
Normally, a dwarf hamster would go after a mouse tail and usually injue the mouse or the mouse would fight back…
* CowRu eventually died from old age and Pinky the mouse at one year old then got adopted by Vanilla an adult rat ..and Vanilla was just as protective of Pinky as CowRu was.