I tried 32.1 very briefly last night on my arch root. Retroarch runs but mpv and kodi core dumped in glx somewhere (don't have the stack traces in front me). I wonder if perhaps the Nvidia binary drivers were compiled with a differing gcc ABI or against an older Xorg. I'm using gcc 8.3.
Bylaws, I notice the config generated by defconfig in your Linux 4.9 repo is different than the shipped config in your image (/proc/config.gz). Are you doing any tweaks other than building from the repos? Is all the code pushed? Can you confirm you're building on all of the default branches in...
I tried cross compiling the kernel using just the following in the linux-switch repo on the switch-dev branch:
export ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu-
make nintendo_switch_defconfig
make dtbs
make -j93
It worked but the image was only 24M compared to your 27M and...