Low storage installation - how to mount zypper cache in tmpfs?

Hello. I have graphical OpenSUSE installation on 2GB hdd. Unfortunately I’m having difficulties with updating OS because package glibc-locales requires too much space for update so I need to put offload zypper cache to tmpfs in order to finish update.

Which directories should I mount in ramdisk?

That would be “/var/cache/zypp/packages”. Or just a directory under there. (This assumes that I properly understood what you are trying to do).