Hi Madhavi, I've worked with stakeholders from various functions (including these), in almost all cases, the key objectives and benefit are the discussions on delivering on what they want (backlog/prioritisation, architecture runway discussions, etc), then deliver on quality/speed of delivery. I wouldn't try to reorganise other functions over which you have no control, instead find a way for your part of the organisation to best work with them.
If you are working in an organisation with a full top-down Lean initiative then there is a chance to better redesign the organisation around value streams. It's unlikely you'd be able to do that (or make it stick) bottom-up.
Rally structure would be best to follow the value streams at portfolio level and then sub-projects for each feature or component teams.
Hope this helps.
Anthony