One question is if you will be using some Xilinx IP, in which case the simulation models likely will be encrypted. If your project doesn’t, I don’t see why it would be an issue using Icarus, etc.

If all you depend on from the IP is data over an AXI/AXI-stream or the like you can use open-source bus-function models (which I understand as librarues you can use that will take care of properly driving something like an AXI interface for you) in your testbench.

I’m a student myself, Im sharing what I know but this might not be how industry does it.