I was trying to make an installation using the wifi interface, but the
installation process failed because the firmware required by such interface was
missing in the installation initrd.

The wifi interface I'm using requires the firmware file rtl8723bs_nic.bin.xz in
/lib/firmware/rtlwifi which in turn is a link to rtl8723bu_nic.bin.xz present
in the same directory.

In the initrd installation image
(https://download.opensuse.org/distribution/leap/15.6/repo/oss/boot/x86_64/loader/initrd)
in the squashfs file parts/00_lib
the directory lib/firmware/rtlwifi contains the firmware file
rtl8723bu_nic.bin.xz but the soft link rtl8723bs_nic.bin.xz is missing.
If it were present, I would be able to use the wifi interface to perform the
installation (tested).

Can the soft links be added in the squashfs image containing the firmware
files?

This is not a problem only for Leap. The links are missing as well in
tumbleweed.