I'm going to make a Quest game. If I use the art assets in the previous PC VR project, such as characters and scene models, do I only need to convert and optimize them without re-modeling?
Depends on how low poly the game is, If the models are relatively high poly you can optimize them, port them, and test it. I say optimization for consoles like the quest 2 is mostly based on testing and see what works. If you need any help or any questions I have a bit of experience in 3d modeling and optimization. Contact me if you need help.