Transacting with your eyeball? Directly out of the Book of Revelations!
[1] I took a strong interest in biochemistry in college and I'm no longer religious.
Initially I thought it's a bloody stupid idea, however at this stage I reckon we need it or a lot of boomers are going to be ones hotted into singing away all their wealth away.
I predict that Worldcoin will get it done first, and will be more dependable than most countries. But it could turn out otherwise. In the end, services that need humanity verification will have multiple provider options and the market will decide.
Government solutions will be opt-out, and only in the most tedious way: Leaving the country, burning your passport and becoming a stateless person. Not recommended.
If there ever was a moat, government has it.
I would trust a blockchain more than my government. My government has clearly been shown to be vulnerable to a < 51% attack. Blockchains don't change every 4 years and decide habeas corpus no longer applies to me because my skin is the wrong color either.