Kaan as a project is not in a state to be shared with other countries for joint development. To open this up, all the development milestones and future tech for Kaan B0, B10 and B20 are already set in stone. There is no tech to be worked on from beginning for Kaan, no tech we need from someone else. Only "tech" being sough after are the F110 engines for the B10; that's it. Rest are to be Turkish. Development of some things can be distributed among other companies, but Turkey still retains the IP for whole aircraft.
If any country wants to be part of Kaan as a customer or as a building partner, agreements can be made. Joint development is not part of it; and except the engine, there's no roadblock any country can put ahead of Kaan's development or production.