How to Set Up a Portable Ubuntu OS on SSD?

Be cautious though! If you install Ubuntu this way, it might end up being less portable since it's kind of tied to the original hardware. If you want true portability, consider directly writing the ISO to the external SSD and adding a persistence feature. It might not be as fast, but it should work on most computers without problem.

Here's what I typically do: First, I disable all other drives on my system and plug in my target USB SSD. Then I boot up the installer USB and proceed to install Ubuntu directly onto the SSD. After that, I verify it boots properly. If you want to use the remaining space for Windows-compatible storage, I boot back into the installer USB and use GParted to resize the partitions accordingly.