From what I can see prolia doesn't come in an Intravenous form so it is likely your gp is referring to Zolendronic acid as @Romla detailed. From what I have read it is usually only recommended following a unexplained hip fracture to qualify for pbs. Prolia injection would be covered by the toe fracture.
And yes...although the risk of jaw issues is rare it is still a risk. Really a twice yeally injection in the GP office is no big deal and might reduce some other risks should you need an extraction.
Maybe a chat again with your GP or even oncologist/breast surgeon about risks and benefits orior goibg ahead. A few more weeks shouldn't make a difference whikst you make informed choices.
Having said that my father had some sort of treatment like this for pagets disease and had no side effect issues. I believe he had for 3 years.