Yes that's why I said actual performance is around 70% less than the "fake" TF figure would imply. Only thing Nintendo cares about is price, and Samsung 8nm wafer is heavily rumored to be at least 1/3rd the price of a 5nm TSMC wafer, $5K - 6k range Vs. $15K - $18K. I don't even think a 5nm wafer will produce 2x more chips per wafer, never mind 3x or better. Nintendo's miser ass is most definitely NOT going to pay a 125%+ premium per chip for better clocks or power efficiency, not a chance in hell.
1.) Nvidia was getting densities of ~43.5Mtr / mm² on 8nm compared with densities of ~119Mtr / mm² on 5 nm, as you can see if you check various Ampere and Ada cards on TPU. So that is already almost 3X the density. And 3X may even be achievable considering logic scales better than cache and the newer Ada chips have a lot more cache.
2.) Even if all TSMC processes are too expensive, it doesn't rule out a newer Samsung process, such as their 5LPE node.
3.) Why did Nintendo decide not to build a smaller chip if their current one is wasting performance in handheld mode, and like you implied they only care about cost?
4.) Why is Nintendo apparently perfectly happy to design on a node that will likely be discontinued in a few years, forcing them to use a newer process anyway?
And regarding Ampere's performance, my point is that its real world performance is pretty close to GCN's, which was also considered to have "inflated" TF figures. So even a 2.4 TF Switch 2 should be enough to exceed the performance of the base PS4.