Both from a die size and power envelope perspective this should be feasible on TSMC 4nm process.
I don't see Nintendo making the commitment and spending the money on such an advanced process. As far as I can remember, Nintendo never has (at least in the past 20 or so years). The company knows it can do more with less (see the Switch). Also, because the SoC will run at such low clocks and low voltages, I wonder if (other than density improvements) the cutting edge is worthwhile. I'd put money on a Samsung process and, in particular, the same process as Orin (Samsung 8nm or a mobile optimized variant thereof).