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)

thank you. As for python, seems it is preinstalled on pi, I assume option you suggested might be also viable initially, I'm not very experienced in python though. Right now I feel interesting challenge on how small I can go with rust+libc while keeping it cross compiling.