In the movie Thor: The Dark World we come to know that once the Reality Stone (Aether) has taken a living being's body as a carrier host, it is extremely difficult to extract it. When Jane Foster asks Odin about whether or not his books tell him how to extract it, he says that information is unavailable:
Jane Foster: Does your book happen to mention how to get it out of me?
Odin: No, it does not.
We have been told that the Asgardians are a very old race, Thor alone being 1500+ years old (as he himself tells us in Infinity War):
Thor: You know, I'm 1,500 years old
Thus, it may be safely presumed that Asgardians are much older than many other space beings in the MCU.
So, the question is, how come Rocket extract the Reality Stone with a handheld device (in Avengers: Endgame), when even the great Odin had no clue how to do it?