You could push Hexnode app as a VPP app into a supervised iOS device. Supervised devices support silent app installation, ie. AppleID won’t be required to install the apps, contrary to the case of installation of apps from App Store. VPP apps are purchased through Apple Business Manager. VPP apps could be silently installed on supervised devices.
Please check out this link to learn more about silent installation: https://www.hexnode.com/mobile-device-management/help/how-to-install-apps-silently/