You actually will need the NI VC2015 Runtime or another compatible Microsoft Visual C Runtime. Since the Visual C Runtime 2015 and higher is actually backwards compatible, it is indeed not strictly needed for Windows 10 or 11 based systems since they generally come with a newer one. However that is not guaranteed. If your Windows 10 system is not meticulously updated, it may have an older version of this Runtime Library installed than your current LabVIEW 2021 installation requires. And that will not work, it's only backwards compatible, meaning a newer installed version can be used by an application compiled towards an older version, not the other way around. You mentioning that the system will be an embedded system makes me think that it is neither a state of the art latest release, not that it will be regularly updated.