Can I paint pre-finished plywood directly, or do I need to prime it first?

If your plywood is pre-laquered, you'll definitely want to sand off that finish first. Once you've done that, apply a primer before your paint. This prep work will make a big difference in how the final product looks!

You don't necessarily need to remove the entire finish. Just scuffing it up with 80 grit sandpaper can do the trick. After that, apply a primer, then paint, and don’t forget to sand lightly between coats for a smooth finish!

Painting directly on pre-finished plywood, particularly if it's a UV-cured finish, can be a challenge. The surface is quite slick, so you'd likely get poor adhesion if you just go for it. I recommend giving it a good sanding to create a rough surface for better paint hold—think about using a more aggressive grit. But if you're going to all that trouble, you might as well choose standard plywood instead! Seems like a lot of effort for not much return.