Oh yes i mean using image frame sequences is 100% a legit way (I've even built a tool to do this, check: Sprite Builder), so you render the simulation/ animations somewhere else, then use the frames as you want. But doing it real-time is overkill, i.e. 3D particles/ assets are in 3D space, and you put sub viewports in your 2D game scenes to preview what's happening in that 3D space. It's not recommended.