Thank you! Currently we are using ParticleInstance modifier to populate the vegetation assets over our (large) game-scenery and I find really convenient to get the single merged mesh by simple Convert to Mesh.
I will test your patch, I believe it will do the job as well, I just think getting a single mesh out of the Geometry Nodes should be an option as well, especially for scenarios with large amount of instances.
This is the demo of the simple joining procedure I would love to see with G. Nodes (something similar):
