I have found a couple posts around the internet and on here on how to remove all but the first letter of every word in a paragraph (or the whole text) using regex and Microsoft Word, but nothing has seemed to work in LibreOffice Writer.
I have been trying to use the Find and Replace dialog and have regular expressions checked in the options.
As an example:
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Would become:
L i d s a, c a e, s d e t i u l e d m a.
Keeping punctuation and case sensitivity would be great. I also am not opposed to using a different method/program for this.
Assuming LibreOffice's regex support fixed width lookbehinds, you could match on the following pattern:
(?<=\w)\w
and then replace with empty string. This pattern will match any word character except those not preceded by word characters (e.g. at the start of a word).
Here is a running demo.p
Edit:
As suggested in the comments, we can optimize the pattern to:
(?<=\w)\w+
This will match entire sub-words in one go, reducing the number of replacement steps.