How can I get my Linux bootloader to install on my external SSD instead of my internal drive?

Another tip is to temporarily disable or unplug your internal drive through BIOS. This way, your system will default to your external SSD and hopefully avoid any conflicts.

This issue is usually due to the installer not placing the bootloader correctly. If your drive doesn't have an EFI partition, that could explain the problem. Ensure the bootloader is placed in the EFI partition, as that’s necessary. And once you get it set up, make sure you use the fallback bootloader file, bootx64.efi, to avoid needing custom BIOS entries.

First of all, make sure you've backed everything up. Playing around with bootloaders can risk your data! Now, regarding the portable SSD, it's worth knowing that running a full Linux installation on varying hardware can lead to incompatibility issues, particularly concerning the OS's components. Instead, consider using a live environment on your SSD. You can install a live version of Linux with persistence, which allows you to save your files and settings and provides better compatibility across different devices. It won't perform exactly like a full installation, but it should be decent for general usage.

The installer might not be set up for a removable drive like you're hoping. Some components are specific to the hardware you're using, and if you want true portability, you'll want to check out the Arch Wiki's guide for setting up Linux on a removable medium—it's super helpful! It outlines what needs to be considered for a non-standard installation. Also, it's a good idea to go through a standard installation process at least once, perhaps in a virtual machine, just to grasp how things work more thoroughly before you dive into the removable setup.

Keep in mind that booting can behave differently based on the hardware. For example, some Lenovo machines can handle eMMC drives while others can't at all. Make sure your BIOS settings are correct and check whether the external drive is connected via the right port, as the type (SATA or USB) can impact how it boots.