Multi-GPU Setup in sway

I will have soon a setup, where my desktop has an integrated and a dedicated graphics card, both AMD, and I already searched but didn't find any good answer in how the multi-GPU setup works. I would like to have a setup where I primarily use my integrated graphics card and can select the GPU for the starting application with an environment variable, similar to primusrun from NVIDIA. I've read that you can use the environment variable WLR_DRM_DEVICES so the first device will be used for rendering and copied to the other graphics cards. But is it possible that you can select another GPU on the fly for more computation intensive applications like games? Another thing I've read that it manages this automatically with GBM, but then again, how am I able to choose which GPU to use? Background information: I'm getting a new CPU which I chose to have integrated graphics, so I have 2 renderable devices. Reason is I want to be able to unplug my dedicated graphics card in software, so I can use it for my Windows VM setup via PCI passthrough, if applications (games in particular) don't work with wine. Before anyone mentions dual os setup, I already have this, but it's extremely annoying if you have to reboot the system to change the OS, especially if you're talking with someone over Discord, Teamspeak, etc. TL;DR: How does multi-GPU setup in sway work?