I tried to install an OS to a USB stick. This is Kubuntu specific.
You need to create a GPT partition on the stick, then you should be able to just use the installer and install on another USB stick.
I went through it, selected the usb stick… was not sure if everything was right and went a menu back, was correct, went forth again, past the install target selection and installed.
Well… turns out the Kubuntu installer (Calamares) selects the first disk always. And that selection seems to reset to default when going a menu back…
I deleted my complete normal disk, with like everything I had.
No Backup no mercy. Luckily did one only a few weeks before. The first since half a year! Damn… had my uni stuff on Nextcloud, a lot of personal stuff synced to my phone with syncthing.