These projects to my knowledge do not release patches by themselves but as you said, rely on Mozilla's work - they take Firefox, strip it out of few features - namely one's that raised concerns, toss in additional stuff from other projects and include own branding. So perhaps these are more "customized derivatives" or "spin-offs"?

Not that work of these projects isn't good - on contrary. Mozilla has violated the trust of its users in last years with features nobody ask for and those folks pluck that stuff out.

Stil, perhaps it's a time for a proper fork that provides own code maintenance, before things will go worse at Mozilla.