Joining the unRAID community and building my first server (congratulate me I guess ). I was looking for a decent USB boot drive when I accidentally discovered in e-waste bin what is probably the best boot drive that you will likely never buy. It is a DOM (disk on a module) and plugs in directly on to a motherboard USB2.0 header. It is also SLC (single level) and "industrial grade". Advertised speeds are basically the highest I've seen for any USB2.0 drive but with ATTO I was able to max 21read/16write (could be my motherboard limitation) but also very impressive small byte rates (everything was above 2MB/s).
Before you click on the link, seems like new these are $100+ , if you can even find a place to buy one because they are not meant for direct sales to consumer. They also have MLC which obviously has lower endurance.
https://www.innodisk.com/en/products/flash-storage/usb-and-usb-edc/usb_edc_vertical_2se
It might be an overkill but if someone needs the best of the best, the SLC model is likely it (MTBF: 3 million hours).
They also have USB-A thumb drive as well:
https://www.innodisk.com/en/products/flash-storage/usb-and-usb-edc/usb_drive_2se#tab3
I hope you learned something today (no I am not Luis Rossmann in disguise, may be).