Writing the iMessage parser in a memory safe language is a step towards a "new paradigm" [0], but more can and should be done by a company Apple's size.
[0]: https://googleprojectzero.blogspot.com/2021/01/a-look-at-ime...
Also Apple is notorious on their bad bounties and on have a bad history on providing researchers with unlocked devices for testing, probably Google found more security bugs in iOS then Apple.
If the NSO Group has been active for a number of years, couldn't Apple make an effort to purchase their products (through some third party, perhaps) and then reverse-engineer the vulnerabilities?
However I also don't think that this can fully solve the problem - if a government creates a sufficiently funded black hat operation (or outsources it to someone like NSO, which is effectively the same thing), it's inevitable that they will find a 0-day sooner or later.
This is going off topic a bit, but I honestly don't know what the solution to this is. The pragmatic truth is that anyone who is a big enough target that it would be worth for a hostile entity to spend a couple million to intercept their communication should assume at all times that their devices are compromised.