For $G$-CW complexes, in the sense that the local building blocks are $G \times_{H} V$ where $H < G$ and $V$ is a $G$-representation, one can define $RO(G)$-graded cohomology theories. Standard constructions from algebraic topology, including Poincare duality, Thom isomorphisms, cup and cap products etc, could be constructed in such theory. See the reference Equivariant ordinary homology and cohomology. (Perhaps not the most canonical reference, but it includes the necessary backgrounds).
Here is the question: is there a way to construct an analogue of intersection product on the "middle-dimensional" cohomology? Is it possible to recover such product by studying intersection behavior of $2$ middle-dimensional $G$-CW subcomplexes/$G$-invariant submanifolds in general position?
Remark: It is well-known that equivariant transversality is hard to achieve. Let's just assume that we can indeed put things in general positions.