No, with the Arctis 7+ you can't listen to PS5 and PC sound at the same time when switching between systems. The headset uses a USB-C dongle that allows you to switch between different platforms such as PS5, PS4, PC, Android and Switch, but it can only maintain a connection to one platform at a time.

To hear the sound from another platform, you need to connect the dongle to the appropriate device and switch the connection. There is no function that allows you to listen to the sound from multiple platforms at the same time.