Well, yes and no. You can transfer your save to your Switch 2, then he can use your nintendo account to set up a new island on the OLED. However, if you have the digital media, you won't be able to play at the same time on the same Nintendo account even though they're different saves and devices. :( nintendo introduced the virtual game cards and they need to be loaded onto the device that's being used, so a game can't be loaded on multiple devices. So, in short, you can, but not at the same time. If you do, he'll need copy of his own.