The second they make this and make it useful in any way, immediately the apps people create will lay bare exactly how bad of a privacy invasion they are, tons of bad press ensuing.
It's definitely not technical hurdles preventing them from making one.
Censorship and alignment (speech, LLMs, glasses, drones, ..) rarely stops negative scenarios, but it slows positive scenarios from existence and competition with negative scenarios.
It's definitely not technical hurdles preventing them from making one.