How to install several Linux Systems on one SSD Disk and make it portable
Here is my instruction. If you follow each step to the letter the whole thing is very simple. When everything is ready you can use your ssd disk on any computer.

Step 1: Get (buy) a Samsung T_7 portable disk of 1TB. In Sweden the price is about $ 300. You can also use a Samsung T_5 or some other brand.The primary differences between the Samsung T_5 and Samsung T_7 portable solid-state drives come down to internal architecture, raw data transfer speeds, and underlying hardware technology.

1. Speed and Performance

Samsung T_5: Utilizes a SATA-based internal architecture. Its sequential read and write speeds max out at around 540 MB/s (real-world testing usually sits around 460–520 MB/s).

Samsung T_7: Utilizes an NVMe-based internal architecture. Its sequential read and write speeds reach up to 1,050 MB/s and 1,000 MB/s respectively (real-world testing typically yields 800–900 MB/s depending on the host system).

The Difference: The T_7 is roughly twice as fast as the T_5 when transferring large files (such as raw video footage or disk images). However, for small, random file input/output (like everyday office documents), the performance gap narrows significantly.

Step 2: For this instruction I used a Samsung T_7. I wanted to have seven (7) Linux Systems installed on the disk. Namely MX Linux for Grub (boot loader) and work, ExTiX Deepin, SlackEX, Exton|Defender, ArchEX KDE, EXTON OpSuS and LFS (Linux From Scratch). I started by booting up MX Linux from a USB stick. Then I used GParted to create nine (9) partitions on the ssd disk as the screenshot below shows.

Step 3: Then I started by installing MX Linux on /dev/sda2. Note that /dev/sda1 shall have the file system FAT32 and the Flags boot, esp. The installer will automatically recognize /dev/sda1 as the EFI partition where Grub shall be installed. When the installation of MX Linux is ready you can reboot your computer. Press F12 or F9 so that you will boot up MX Linux from your ssd disk.

Step 4: While running MX Linux from the ssd disk you shall delete all files in the folder /etc/grub.d except 00_header, 05_debian_theme, 40_custom and README. The folder shall look like the screenshot below shows.

After that you shall edit /etc/grub.d/40_custom to make it look like this…

Then just run the command (as root) update-grub. Check that /boot/grub/grub.cfg has the same content as the mentioned 40_custom file above.

Step 5: Now you are ready to go on and install the other six (or more) Linux Systems you want to have on your ssd disk. Start with ExTiX Deepin (for example). After every installation you shall edit /etc/grub.d/40_custom on /dev/sda2 (where you have MX Linux installed). Add boot lines for ExTiX – see below:
menuentry ‘ExTiX Deepin 260911 (sda3-Samsung_T7)’ –class debian –class gnu-linux –class gnu –class os $menuentry_id_option ‘gnulinux-simple-1a15cc22-6b18-4677-8c42-ddaa643bb8c1’ {
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_gpt
insmod ext2
if [ x$feature_platform_search_hint = xy ]; then
search –no-floppy –fs-uuid –set=root 1a15cc22-6b18-4677-8c42-ddaa643bb8c1
else
search –no-floppy –fs-uuid –set=root 1a15cc22-6b18-4677-8c42-ddaa643bb8c1
fi
linux /boot/vmlinuz-7.1.2-amd64-exton root=UUID=1a15cc22-6b18-4677-8c42-ddaa643bb8c1 ro quiet acpi_backlight=vendor splash acpi_rev_override=1
initrd /boot/initrd.img-7.1.2-amd64-exton
}
####################################################
After that run the command update-grub (in MX Linux) again. You’ll find the correct UUID with the command blkid /dev/sda3. Watch the screenshot below. A Universally Unique Identifier (UUID) in Linux is a unique 128-bit number used to identify storage partitions, filesystems and software resources reliably across systems. 

Click on the picture above if you want to see it in full scale.

Finally you can have a look at my 40_custom file when all seven (and three more) Linux Systems are installed.

exton/260914