(1) to such a degree that it would allow the attacker to create new blocks at will.
Assume 1 bitcoin is $50k; break it only once a day and make over 15 million × block reward a year. I doubt many governments could resist.
I mean if you break either the hash or the signature, then there are bigger fish to fry than just Bitcoin. You'd essentially be on your way to breaking much of the crypto used to secure significantly more valuable information -- the kind of information you measure with human lives rather than dollars.
Actually, if you (or more likely a nation state actor) did break either the hash or signature, you'd be crazy to reveal that fact on something as trivial as Bitcoin. That'd be like breaking ENIGMA and just using it to publish the German weather reports lol.
And it is likely to be very obvious and public.
You will crash the market, so can't really do that multiple times.
And if you can Crack this there are better targets