This repository contains a variety of SDDM/KSplash/GTK/Grub themes in various states of work-in-progress.
For your convenience, an "install script" is included...aka, it's just a cp line. In theory, it will ask for sudo to dump the files into /usr/share/<place>. You can look at the script "in-depth" if you are afraid of something malicious.
As a short note, all of the QML/QT themes were written importing the latest libraries from QT5.7 (QtQuick 2.7, etc.), though the themes don't require anything from said latest libraries. As such, if you aren't using the latest QT5.7, you can change the import lines to the closest lower whole number (aka import QtQuick 2.7 -> import QtQuick 2.0) and they should work on any QT5 version.
Notes: Currently there is only a single script for previewing/assisting in creating grub_init_tune (original script). It can accept files, a environment variable GRUB_INIT_TUNE, or a somewhat janky custom notation that removes most thinking.
The separator ('*'), default octave (octave 4), and default tempo (120 BPM) can be customized.
The notes were tuned to A4 or 440Hz based off of the equal tempered scale.
GRUB_INIT_TUNE Format:
<tempo> <freq> <duration> <freq> <duration>...
Custom Janky Format:
<tempo> <note>*<duration> <note>*<duration>...
Notes on custom format: