If Williams really took a step forward as a whole that would be quite something

It would, but its unlikely. Even Sainz in the post-race interview did not seem hopeful about a repeat performance with the races remaining.

(especially as no one is bringing upgrades for this year anymore at this stage).

And we know with Williams they never really did upgrades for FW47 (as its essentially their 2024 car) deciding instead to save their development budget for the post-rule-change 2026 Williams car.