Sxos folder IS accessible natively using tinfoil no PC or phone
Use File browser>Sdmc/sxos
You can even copy and paste.
I just did it.
You can also access it with tinfoil on a PC or Phone in MTP with a USB cable as well.
Just did it.
MTP allows NSP installs. Just drop in the install folder.
You can access the ENTIRE SD in Hekate in UMS too using a USB cable.
You can update the cheats file using the all-in-one updater. Or a variety of other Homebrew methods.
https://github.com/HamletDuFromage/aio-switch-updater
Old unsupported depreciated version
https://gbatemp.net/threads/switch-cheats-updater-update-your-cheat-files-from-your-switch.561878/
I think you're making this a little bit harder than it needs to be.
You do not need an internet connection for MTP. Period. I'm in airplane mode
Heres a payload program that works
https://github.com/suchmememanyskill/TegraExplorer/releases
Choose your destiny,
As far as using your phone that will depend on your phone. There is your weakest link.
are you use newest tinfoil homebrew?
i use 2020 tinfoil sxos folder just cant access...