Happy to hear you found a solution. 
I admire your persistence. 
FAT32 is old, very old, and has limitations, for Porteus it's only needed for the /EFI and /boot directories on UEFI machines. All other formats are fine for Porteus files and user files.An interesting app Flatpak.
A /var/lib/flatpak folder exists in your flatpak-1.12.7-x86_64-2alien.xzm module but no files in it. Which brings up the question who/what/why is writing to it. The echos you posted look like dupes of the same line of code.
And no flathub.org Bottles module in your flatpak1.12.7.tar.gz file!
