I'm not sure if they've done that yet. If I'm not mistaken, I believe Microsoft has only backported web-based features from Windows 11 to 10 at this point. The File Explorer redesign kind of seems like a lot to backport to 10, especially with its current end-of-support date unchanged.
Oh, okay. Yeah there probably are some third-party file explorer apps in the Microsoft Store that have tabs. That I definitely wouldn't be surprised by.
Yeah, the first-party Explorer definitely wouldn't be available through the store. Since it's a core component of the Windows system, I doubt Microsoft could separate it from the OS without much difficulty.