Is it ok to ask a potential PhD advisor for more information about their future grants?
I think you can certainly ask (nicely) for some more details about her ideas and the research she proposed as part of the grant. Especially so if this is going to be something you end up working on, or close to your own projects. You are, after all, possibly going to work for her! I don't think she will think anything else than you having interest in her research, which is quite positive.

However, don't ask for the grant proposal (i.e. the written text) itself, as it could be seen as assuming. Ask the questions you have, and let her decide if she wants to reply or simply give you the document to read.