> I don't think you could built a fan-less x86 laptop.

Sure you can, they’re readily available on the market, though not especially common.

But even performance laptops can often be run without spinning their fans up at all. Right now, the ambient temperature where I live is around 28°, and my four-year-old Ryzen 5800HS laptop hasn’t used its fan all day, though for a lot of that time it will have been helped by a ceiling fan. But even away from a fan for the last half hour, it sits in my lap only warm, not hot. It’s easy enough to give it a load it’ll need to spin the fan up for, but you can also limit it so it will never need its fan. (In summer when the ambient temperature is 10°C higher every day, you’ll want to use its fan even when idling, and it’ll be hard to convince it not to spin them up.)

x86-64 devices that are don’t even have fans won’t ever have such powerful CPUs, and historically have always been very underpowered. Like only 60% of my 5800HS’s single-threaded benchmarking and only 20% of its multithreaded. But at under 20% of the peak power consumption.