I have no idea why this would really be different than adding the ADU to a lot where your house is already located.

If the house you want will fit on the lot, then it sounds like a good idea. Make sure you pick a good architect, so it doesn't look like you stuck a new house in front of an old house ...

Look up Kol and his Portland, OR DADU. He built a lovely DADU on the back of his property and rents out the front house. He is a great advocate of DADUs in general and is featured on several blogs which would be a great resource for you on this.