USB boot has been possible since the Raspberry Pi 2 Model B (v1.2), but it has only become really worthwhile with the Pi 4. Here is some information, tips, tricks and opinions explaining why and how.

The Raspberry Pi 4 Model B with 8GB of RAM is available now for $75. In order to map all 8GB of RAM into the address space of a single process, a 64-bit operating system is needed.

The conventional standard OS 'Raspbian' is built as a 32-bit OS, and can be used with this Raspberry Pi equipped with 8GB memory. However, due to the 32-bit limitation, a single process can only ...

To take full advantage of this extra memory, a 64-bit version of the foundation's official operating system, Raspbian, has been released in early beta, though it's now called Raspberry Pi OS.

Make sure you select Raspberry Pi 5 from the list of options, followed by Pi OS 64-bit. If you don't have an adapter, install the SSD using the steps below but leave the SD card plugged into your Pi.

To take full advantage of the increased amounts of RAM, the foundation is also releasing a 64-bit version of its Raspbian operating system in early beta, renamed to Raspberry Pi OS.

Of course, some of this depends on the USB adapter, and [tynick] recommends a particular one that seems to work well. The Pi 4 is already fast, especially with a 64-bit OS.

I managed to build a portal wireless router for my travels using a Raspberry Pi 4 with RaspAP and a USB Wi-Fi adapter.