Looks like nice human written rust code, I wonder if for your use case it might have been easier to write a small python script to use glob and pathlib to just add your emojis or note which is a file or dir since that shouldn't be super slow and would be using less space too(assuming you have python on your pi)

For comparison: GNU coreutils ls 9.4 is 139 KiB on my system.

BusyBox v1.36.1 is 2.1 MiB and has 272 tools which is just about 7.6 KiB per tool, so when it comes to space efficiency BusyBox is probably hard to beat.

The (probably statically linked) 9base-6 Plan 9 ls is 961 KiB.