Media player playlist (such as .m3u8) are basically text files that contain list of multimedia files to be played in specific order. As such you do not need to convert .m3u8 to .txt files, you can open playlists using any text editor and edit them should you need it, regardless of their actual file extension.
Convert UTF-8 M3U playlist to Simple text file.
We found 2 software records in the database related to .m3u8 to .txt file format conversion.
Microsoft Windows software - convert m3u8 to txt on Windows
A free source code and text editor for Windows
Convert from m3u8 file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned m3u8 to txt. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert m3u8 to txt on OS X
The default text editor in Mac OS X