I don't think pinning deps will help you much, as these incidents often affect transitive dependencies not listed in package.json. package-lock.json is there to protect against automatic upgrades.

I know there are some reports about the lockfile not always working as expected. Some of those reports are outdated info from like 2018 that is simply not true anymore, some of that is due to edge cases like somebody on team having outdated version of npm or installing a package but not committing the changes to lockfile right away. Whatever the reason, pinned version ranges wouldn't protect against that. Using npm ci instead of npm install would.

No, it doesn't solve it - but it might minimise the blast radius - there are so many unmaintained libraries of code that indeed one compromised minor patch on any dependency can become a risk.

That's sort of the thing - all of these measures are just patches on the fundamental problem that npm has just become too unsafe