[nunobrito]

Sorry to say this, you don't have a negotiation position.

At worse, they will fool you thinking they will buy something, just to extract the deeper details and then think they can do it on their own as you mention. Happens often.

Best bet is being hired to join their team, albeit I'm not sure how pleasant that would be for you. If you see a company/manager that you want to join, this might be a good opportunity.

In either case, your intuition will be the best help. If you don't feel you can trust someone you are negotiating on this topic, very likely you won't get a good outcome.