Sorry for the late reaction.
I have the appliance also and did not install it myself and it is there. I did install the appliance about 3 years ago and did an upgrade along the way. Never installed busybox or busybox-ed myself.
The only extra i did install in the appliance are:
I did manage to install it using just ignore all dependencies. and it works.
And it came with Griommunio:
2023-10-01 23:30:37|command|root@mail|'zypper' 'update' 'gromox'|
2023-10-01 23:30:40|install|gromox|2.13.41.19134b4-lp155.27.1|x86_64|root@mail|grommunio|36552da6bb525723c9142c9d706bda41ca9403dde22a115d11737af6f6c56dd9|
2023-10-01 23:33:40|command|root@mail|'zypper' 'dup'|
2023-10-01 23:33:40|remove |systemd-presets-branding-grommunio|2022.12-lp154.1.2|noarch
2023-10-01 23:33:40|install|Mesa-libglapi0|22.3.5-150500.75.2|x86_64base|b6a6d6f000c4272a58dcb55ce3d69676a730862fa2b6704257d5ce08959103b3|
2023-10-01 23:33:41|install|branding-upstream|12.3-lp155.2.4|noarchbase|49fae0ac5f61badd29f827b1d6b5e07daa355b712bee9f7eabf7644527b6793f|
2023-10-01 23:33:41|install|btrfsprogs-udev-rules|5.14-150500.8.23|noarchbase|e5c519fd096d4cf29e428ce0655066affd4b298521017f8281e0ce4b2b05d1b8|
2023-10-01 23:33:41|install|busybox|1.35.0-150500.8.2|x86_64||base|5df1698c95810113aef612ae9e1277a9cbf73b989c087137bc31ca92ed104288|