$450M is a rounding error when it comes to equipping an air fleet with jet fighters.
(This is also a good moment to be doing it, under Biden, who's OK to do business. Contrast that with Pakistan's time out in the cold, under Trump. Best do it now, just in case 2024 brings back a Republican POTUS. Perhaps even Trump redux...)
When Pakistan gets around to replacing its F16s, I suspect they won't be buying US gear. For now, it's a good way to keep their fleet readiness up. The "influence" can be a bit overstated as well: Iran kept using their F14s for decades, without much US influence.
Also the J10 seems to be a capable 3rd generation jet, designed in late 80s, first flown in 1998. That's not something you'd want to splurge much money on to equip an air force from scratch now.
I'd also give China a decade or so before I'd consider some of its traditional weapons fully on par with Western ones: a lot of their gear is Soviet/Russian derived (and we know how well those work right now). They haven't displayed that much aerospace capability (yet) and have a history of unauthorized copies of Russian jets. Jet engines are a hard tech to master - something like a modern passenger jet has a huge chunk of its cost and value accounted for in its engines.
But the Chinese are learning. Their latest aircraft carrier is using electromagnetic catapults, something even the US Navy is struggling with on their latest carrier. Their carrier-killer ballistic missiles - at least theoretically - are a potent menace to US carriers. I'd expect the most Chinese capability when they design things that the West has not done yet. Something like killer autonomous drones would play to their strengths in software and AI.
Last, when it comes to jets, I suspect we are coming to another inflection point - how well will stealthies like F35s work in practice? How viable will unmanned fighter jets be in 10-20 years? Look at the general disruption in military doctrine apparent from the Ukraine war. For a country like Pakistan, hedging their bets a bit and waiting things out, rather than committing immediately to what might be an outdated weapons platform in 20 years may not be such a bad idea (a 1960s equivalent was when all the F104/F106 interceptor type aircraft got ditched due to threat evolutions). The US is already talking about 6th generation jets, which, almost, implies a recognition that all isn't rosy with the F35 program and its planned 30-40 year time horizon.
Jet fighters are a long term commitment. Canada is still flying its F18s, first delivered in 1982 (which says a lot about our procurement procedures and military budget...).
And, if I were a Pakistani citizen/taxpayer, I'd be applauding this, unusual, prudence.