Further to the experiment with the SD card I can say there have been no problems at all. I just cloned the data from my external HD so there have been no issues with switching pointers that Mike mentioned. I cannot see that it is any slower than a mechanical HD either.

So with those results I decided to try it on a USB memory stick to see how that worked. Again it works fine, no issues and the speed is pretty much the same as far as I can tell without using a stopwatch. The stick I used is a SanDisk Ultra Fit USB 3.1 Flash Drive 256GB. It is a tiny device and not likely to be damaged when plugged in to a laptop.

https://www.amazon.co.uk/gp/product/B07857Y17V/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1