Once the bootloader is appropriately configured, you can boot straight off an SSD with Raspberry Pi ... earlier implementation on the Raspberry Pi Compute Module 4. Video after the break.
When the Raspberry Pi 4 was released ... advantage of the new USB3 ports. The Pi 4 doesn’t yet support booting from USB, though along with PXE boot, it is planned for a future update.
They're more often seen as PCIe 4.0 upgrades to handhelds like the Steam Deck and ROG Ally lately. Using an SSD is particularly important if you're actually trying to use the Raspberry Pi 5 as any ...