OpenStack connect two subnets from different projects

in my OpenStack setup I have one tenant with different projects and I'm trying to figure out what would be the best approach to make communication between the subnets 10.200.0.0/24 <-> 10.202.1.0/24 of two projects possible (see picture below).

Would that be by creating a shared network and connect GW01 and GW02 to it with static routes? or is there a thing such as "shared router"?

I am a bit lost in the endless possibilities of OpenStack and would appreciate any help/hints.

I would not dare to claim that I have the 'best' approach for you. I can tell what my initial idea would be.

You can share networkB with ProjectA using the instructions here: https://docs.openstack.org/neutron/latest/admin/config-rbac.html. Now if you create a router in ProjectA, you can add interfaces for it in the subnets in networkA as well ass the subnets in networkB. Because the router knows both networks, you don't need to add static routes to route between them.