Mike, you should mention in CAPSLOCK that some of your tutorial doesn't work on MARIKO Switch. I did my research as well and with SYSNAND 13.0.0, no SXOS could be run via Emunand.
Everything up to the "Extras" can be done on Mariko switch,
there's no need to update your sysnand & you're correct you can't go above 11.1 I believe,
My SXos is still 10.2 & I upgraded the Atmosphere to 13.1 & it all works fine - this is a great guide.
I practiced first on an old SD & it was fine, the new card didn't work with EmuTool for the second bin transfer so I had to use DD to transfer the bin over, there's tutorials on this site for doing that too.
You'll need some homebrew app to change the boot file between the SXos one & the SXtools one to change which OS boots.
So I ended up using this guide plus another tool to change region on my China Tencent switch from Chinese (cannot change language) then after changing region I could change the language to English.