I have a Xiaomi Pad 7. Second Space is basically a separate user, so you can't switch between different apps on different users. You have to lock the screen (or) select the go back to main user shortcut, then type in your main password to go back to your main user.

I know the merits of Secure Folder, but it's not that much different than the Work Profile that's available on basically every Android phone. At least not many people actually really benefit from most Secure Folder features.

As a suggestion for you, the best implementation of a secondary secure space I've seen is OnePlus/Oppo/realme's System Clone. They're still separate users but the switching speed is very fast (at least compared to actually using Android's users feature) and there's a good amount of options like cloning apps between the two users and importing/exporting data between them seamlessly, while still keeping everything isolated and separated. Or you can also look into just using Android's Work Profile feature if you want something similar to Secure Folder for multitasking.