The N3 production line isn't necessarily shared with. N5 , N6 , N7, etc.
N3 is only just gone into 'at risk' so it was mainly folks submitting experimental R&D wafer starts up until recently.
The number of ASML EUV production units assigned to the N3 production line will change over time. The capacity is only "fixed" until TSMC lights up more fabrication units assigned to the line. It doesn't stay constant forever.
As far as Meteor lake being a "fantasy unicron".... Intel is already making them in low numbers.
"... Individual chiplets are visible in this closeup of Meteor Lake test chips that pave the way to the PC processor's release in 2023. Intel's Foveros technology bonds the chiplets into 3D stacks. ... "
The chipmaker's come-from-behind strategy is risky and will take years, even with government subsidies.
www.cnet.com
Picture of several packages. Each package has four tiles (chiplets ). Not using fully functional TSMC tiles/chiplets here but the pictures are of the packaging R&D being flushed out.
They have powered on the. "compute" tile. ( the big tile in the packages above )
Meets all expectations.
www.tomshardware.com
Now some folks will label these as "rumored" products because not shipping in the store and can't order from Newegg or pick up at Microcenter.
But already in flight. The GPU is likely one of the relatively smaller tiles on the package. Smaller means Intel can get more tiles out of a single wafer than Apple can for most of the M-series. Intel is making the biggest tile there in their own fabs ( Intel 4 in low volume at the moment. ). Intel isn't asking TSMC to make the "whole thing"; just a part of the package.
These don't have to be "big" GPUs. Just the ~30 Xe-Core for an iGPU for the mainstream desktop product. (probably smaller than Apple's GPU cores and definitely smaller than CPU+GPU+kitchen sink the complete M-series SoC dies have. ) . Extremely likely that Intel will eventually have a wide range of GPU dies on TSMC N3 , but they don't need to launch them all at once and as soon as possible. Intel can phase into the N3 production capacity growth over time.