wl-clipboard has to be installed in the system and it is not mentioned anywhere in the readme
By digging through the code I figured out why I have only 'true' in my clipboard after executing the function. Now it became clear, that I don't have wl-copy available. There is no message in such scenario or anything to indicate something is wrong with the configuration.
Edit: And now I've figured out that this functionality works only on wayland.
Switched to to_clip = false. Now I have a message that "the file was saved" displayed, but there is no file anywhere on my filesystem.
Edit2:
This time I had to enable the debug mode via config file, execute line, read the messages and it turned out it was a missing colorscheme.
Fortunately this time the readme mentioned this issue and I could solve the issue. but the readme says:
require("silicon.utils").reload_silicon_cache()
while I had to use the empty object for opts with:
:lua require("silicon.utils").reload_silicon_cache({})
#27 should handle this more gracefully, let me know how it goes for you