Hello dragnet.
Which tutorial are you referring to? There are two in Gladys?
[Tutorial] Transfer a complete Gladys installation to a USB drive
New YouTube video: Install Gladys on Raspberry Pi with an external SSD for beginners
Yes, my Rpi3B+ works with an SSD, but I can’t use a USB hub, so it works without. However, it’s not straightforward. Try Pierre Gilles’ (Fondation RPI) one, that’s the one that worked for me. Good luck