You have to know the package name of the samsung gallery app, then copy and paste it into the Allowlist under the "Android System Apps" setting. According to this site, the package name for the Samsung gallery app is com.sec.android.gallery3d Once a system app gets disabled, I don't think there is a way to re-enable it without a factory reset. Therefore, I would suggest factory resetting the device and make sure the Allowlist setting is saved before re-enrolling the device in the SM network.
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