Linux always has about 10 different ways to do anything.
This is how I do installs to USB or SD card drives.
This is talking about a USB flash drive, but the same procedure works for an SD card.
Do all of this from a running Fossapup64 9.5.
It already has the needed programs.
Drive labels are going to depend on number of drives on the computer.
So, you do need to be careful to select the correct drive label, when offered to select.
This is what I do.
Using Gparted program
Delete all partitions on the USB drive, so it has all unallocated space.
Setup the USB with 2 partitions.
First one, small 300MB, fat32 format, flagged boot. (location for boot loader files, boot partition)
Rest of drive, whatever other partition(s), but one ext3 or 4 format. (location to put frugal installs)
(this is UEFI standard requirement, and some computers, look for a fat32 partition, for boot loader files)
Run Frugalpup Installer main program.
On the main window are selection buttons.
Select the Puppy button, to do the install.
Make sure to select the USB drive you want to install on.
Go through install process, selecting to install to the ext formatted partition.
Note:
When selecting the partition to install to.
A window pops up, giving option to make a directory(folder), to put the frugal install in.
I make this directory and usually name it, the name of the Puppy version.
Carefully read that windows info.
Press enter, makes the directory, not the OK button.
complete the install.
When it gets back to the main Frugalpup window.
Select the boot button.
Select the location of the frugal install, on the USB stick.
Select the small 300MB partition on the USB stick, as location to install the boot loader. (may need to scroll the selection window)
Select the boot loader type.
UEFI
mbr ->legacy bios boot
both
You can install the UEFI for UEFI computers, mbr for legacy bios computers, or both, to boot anything.
The UEFI will also install the needed files, to support secure boot enabled in UEFI.
When you first boot the USB stick, on a UEFI computer, with secure boot enabled.
A process will start, to allow you to install the Puppy security key, to the computer.
It will add this Puppy key, to the other ones, loaded on the computer.
Note:
Not all UEFI computers are the same, for booting from a USB stick.
Some may require secure boot disabled, CSM enabled, or legacy boot enabled, to be able to boot from a USB stick.
So, for those computers.
The mbr boot loader will work, because the UEFI bios, is basically in, legacy bios operation.
To put more frugal installs on the same USB stick.
Do the complete process again, for the new Puppy version.
When you run the boot loader install.
It will make entries, for all installs it finds, on the USB drive.
If you get lost or not sure what to exactly do.
Ask about that and only talk about that.