@coplate: I don't think we can mangle FB02 updates like that, the package might not be signed itself, but individual files, manifest included, are ;/.
I do not know how the initrd updater deals will missing files (i.e., we can remove data.stgz & its sig, but we can't remove it from the manifest). I don't *think* it's blindly going to accept that missing file without throwing an error

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EDIT: Huh, might be worth a try though, since it's already listing three possible filenames for the stgz in the manifest, a formatting tweak I'd never noticed before

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