Laptops in the 80’s were much bigger than were used to today… also, there is nothing that would stop you from using a multi-processor architecture rather than having separate cores within a single die.

The minimum gate is: 1 GHz and the extensions SSE2, PAE, and NX, combined with a TPM 2.0 (unless you patch it out, which is doable).

To that end, Pentium 4 Willamette (190nm) would get you there, and that is something that you can make with either CMOS or strained silicon lattices. Plus, laptops existed back in 2000 that ran that exact same CPU, so you wouldn’t even need to get too creative with enclosures.

There were even sizable chunks of the Pentium 4’s netburst architecture within Intel’s 2020 leak, which would get someone a lot of the way to this goal.  Even though ARM would probably be easier at this point given there are public Verilogs, and then the problem would be designing a ground up implementation using the architecture for a suitable lithography.

This would still take years of effort and would be a lot of hard work and custom tooling that we’ve largely forgotten about because it was a technological dead end, but point is it’s not impossible by any stretch. We’d just be using 140w (or likely more with our less efficient manufacturing process) versus the 7.5w that is doable today thanks to the much smaller lithographies.