There are laptops sold with NVidia's high-end 4090 graphics chip, but it's a power-constrained mobile version appropriate for portable machines. A Chinese-language blogger modded themselves a beast of a machine with a full desktop-class 4090 card. This thing weighs 15 pounds and its battery life is a Borgesian map of nothing (one must plug it in). Videocardz translates and summarizes the video.
The key upgrade is the graphics card. It uses a custom blower-style RTX 4090 model with a 450W TDP (so it's not a 4090D). This card also has the power connector conveniently placed for a laptop configuration. The modder even added a custom speaker system featuring a 2x 20W setup. According to the mini-review, the system is very stable, with the GPU easily maintaining its 450W TDP specs. The card runs at 70°C and can play games like Naraka Bladepoint for hours without any stability issues. This mod is actually a pre-order customization, and the modder says it's possible to create one for a Core i9-14900K as well (up to 200W). What's missing from making it an actual laptop is the battery. This "laptop" cannot run without being plugged into a power supply at all times. The modder completely omitted this step, likely due to the high power requirements of the setup (which could easily reach 600W or higher during peak usage).
At this point it's really just a bizarre desktop form factor; it seems more sensible to create some kind of briefcase computer mostly made of lithium.