The below is not because young people don't want to leave, it's because they can't afford a place to live by themselves since salaries are shit and those countries have insane realestate bubbles proped up by foreigner "investors" (making the prices even more insane in terms of local incomes).
What often happens is that those young people who leave, leave not just their parent's home but also the country itself (for example, half of Portugal's University graduates emigrate when they graduate)
The EUR absolutelly is - the EU is a big stable open economy with large Financial Markets a freely trading currency and deep Treasuries markets.
It's not by chance that over the last 2 decades mainly the EUR has taken a bigger and bigger slice of foreign exchange reserves away from the USD, with by 2025 the EUR being roughly 1/3 the amount of USD reserves (see here).
(That said, looking at that data, the EUR and USD foreign currency reserves have barelly moved since 2017)
Agree on the RNB not being ready - China's currency isn't freely traded and neither are their treasuries, and access to mainland Financial Markets is highly restricted. That's reflected on the above mentioned foreign exchange reserves where the RNB is but 1/10 of the EUR reserves.