I agree it probably won't happen (it's after all not the first time the UK government has tried similar nonsense). But e.g. the EU settlement scheme offered tw

I agree it probably won't happen (it's after all not the first time the UK government has tried similar nonsense). But e.g. the EU settlement scheme offered two options for me to scan my passport: Use a phone with NFC, or go to a government center to have it scanned there. There's nothing fundamentally preventing them from offering a similar set of options for this nonsense where the fallback for anyone who hasn't got a smartphone would be to go to a government center and tell some government official that they want to be authorized to watch porn (though given the current government, more likely it'd be outsourced without proper tender to a company run by the friends of a government minister). I'm going to predict that 1) a contract will be negotiated with someone with political connections, 2) the scheme will be silently scrapped after significant cost overruns and failing to produce a viable solution.