Since she is only 10 weeks old, I wouldn't take her on walks just yet, she isn't old enough to have finished her shots and it's possible she could easily pick something up.
But, I would wait to buy the buddy belt based solely on how much it costs and since your puppy will most likely grow out of it. There are a ton of options out there, unfortunately because yorkies are so tiny it's really difficult to find a good harness small enough. About how big around is she right now?
This one looks just like the buddy belt, but it's not much cheaper than it and its smallest size appears to be 9inches, that may be a bit big for your pup but it's worth it to measure her chest so you can make sure you're getting the right fit for her.
Choke Free Step-In Harness for Small Dogs
Here is a puppia harness, but it may be too large for how small she is...
Amazon.com: Puppia Soft Dog Harness, Red, Small:...
You could also look into cat/kitten harnesses for now, I believe the sell them at petsmart, but I could be wrong.