> As long as we have free capital flows there's no way around this
I think that's the gist of it, and as such I also think that free capital flows will be massively restrained in the scenario you mention (a scenario which I also find very likely).
A similar thing has just happened with the freedom of movement for people, a "right" that the great majority of us had taken for granted, and then Covid came and that "right" was forgotten about like it never had existed.
The ECB is a lot more politically constrained than other central banks. It doesn't have a single master but is beholden to various degrees to the member states of the EU and especially Germany which is utterly paranoid about currency devaluation.
Don't forget the ECB raised rates during the onset of the financial crisis circa 2007-8 when everyone else was cutting desperately because of their inflation targetting mandate.
Most of the developed nations are competitively devaluing their currencies. If one country does it, they gain a trade advantage: their exports are relatively cheaper on the world market, so consumption flows to their industries and makes them wealthy. Therefore once one country does it, they all have to do it, lest all their export industries become uncompetitive and they lose those jobs.
I've heard some speculation (nicely backed up by data [1]) that the real reason we couldn't follow through with monetary tightening 2015-2018 is because it created a carry trade of investors borrowing in Euros and investing in dollars [2], which led to a continual outflow of dollars out the door.
If hyperinflation hits it will likely hit nearly all the developed world in short succession. If the dollar goes, all investors are going to dump dollars for Euros, but if they do that the value of the Euro will skyrocket, which means European exports will become super expensive and Euro-denominated debt will be harder to pay off, which will spur European central banks to dump more Euros into the system. As long as we have free capital flows there's no way around this: inflation in one fiat currency will lead to inflation in others. That's why people are looking for non-fiat currencies. (You're right that tradable assets like stocks can fulfill this job rather than cryptocurrency, though.)
[1] https://www.pimco.com.br/-/media/global-assets/resources/edu...
[2] https://www.ft.com/content/fe099068-169d-11ea-8d73-6303645ac...