Hi. I know you didn't as me but I know some tools that may help. But perhaps i should warn that those tools are for local use.
But for doing a img2mesh there are huyuan3d based worlflows, not really game-ready in my opinion but maybe can help. Or 3D gen studio, but i never used it, so i can't talk about it.
For creating art in PNG format I'd recommend Krita with the plugin Krita AI Diffusion since you can edit the image while you made them and also can made the background transparent by just selecting and erasing it.
Another tool i recommend to background removal is RMGB-2-Studio, since is just drag and drop and also allows to process a bunch of files at once.
Hope may help. :-)