I've had this same issue, with Aurora Store and some other apps too. (The only issue I've had with GrapheneOS.)
So, what if I want to keep those apps (especially Aurora store and my VPN app) in my main profile, but also want to install those apps additionally in another user profile (so I can install and use certain widely used 'consumer apps' for occasional use from there).
I keep getting the same message as OP there.
Would anyone have a solution ?
Ty