Thanks @arvidjaar & @karlmistelberger for your help & suggestions.
Strangely the docker image for Tumbleweed comes with busybox-which
I tried to uninstall it but less requires /usr/bin/which
In the end the solution was to install the which package :
sudo zypper install which
Loading repository data...
Reading installed packages...
Resolving package dependencies...
Problem: the installed busybox-which-1.36.0-26.2.noarch conflicts with 'which' provided by the to be installed which-2.21-5.8.x86_64
Solution 1: deinstallation of busybox-which-1.36.0-26.2.noarch
Solution 2: do not install which-2.21-5.8.x86_64
Choose from above solutions by number or cancel [1/2/c/d/?] (c): 1
Resolving dependencies...
Resolving package dependencies...
The following NEW package is going to be installed:
which
The following package is going to be REMOVED:
busybox-which
I will have to report this issue to those providing the Docker image.
Thanks for your quick help - I used SUSE long time ago (versions 9.0, 9.1, 9.2) and I’m considering it again as I’m moving away from Ubuntu & POP!_OS.