Hello,
To whom is interested: Preamble:

Since KDE-5/Plasma-5 is very difficult to get a homogeneous desktop appearances, for me as lover of 'breeze-dark' is much more difficult. After long recherches I found the solution and don't want to deprive you.
Under KDE-4 was 'qt4config' app (or something similar) , under KDE-5 I think the name was 'qt5ct' but to be installed over a PPA.
Since we cannot use PPAs... we need another solution also practicable for newbie like myself.

1. Tell DE (KDE-5/Plasma-5) to use always is own session. That was reported as bug for 'kdesudo' https://bugs.kde.org/show_bug.cgi?id=353263 but is necessary also for the appearances especially if you want 'Gtk'-apps have exactly same appearances like the 'Qt's, don't ask me why but without this you can stop go further. If not...:
1.a. Create a text-file e.g with Krusader as admin or over konsole

/etc/sudoers.d/workaround_kde5

1.b. Open the new created file, insert following text/code, one emty line @ end, save and close.
Note: by creating file with 'krusader' the editor will opened automatically!

Defaults env_keep += "KDE_SESSION_VERSION KDE_FULL_SESSION"

2. Rename following two files preserving you to change the configuration @ your intent

mv /etc/xdg/Trolltech.conf /etc/xdg/bak.Trolltech.conf

mv /etc/gtk-3.0/settings.ini /etc/gtk-3.0/bak.settings.ini

3. Create SymLinks to the modifiable configurations-files

ln -s ~/.gtkrc-2.0 /etc/gtk-2.0/gtkrc

ln -s ~/.config/Trolltech.conf /etc/xdg/Trolltech.conf

ln -s ~/.config/gtk-3.0/settings.ini /etc/gtk-3.0/settings.ini

4. Logout and login again or restart the system, finish. Enjoy

From now on you will get the same Colors, Icons, Fonts, etc. configured through 'systemsettings5' and Systemsettings as admin/root. Start 'systemsettings' over 'KickOff' or 'Alt+F2' and insert:

systemsettings5

Start 'systemsettings' as admin/root through 'konsole' with:

sudo -i systemsettings5

Note: A restart of system or logout/in is not necessary, sometime you are recommended to restart the actual running apps

Test: Start both 'Qt' and 'Gtk' (Dolphin, Kate, Krusader, Gimp, etc) apps to see the results even with admin-rights like 'Synaptic' over 'KickOff' or:

sudo -i krusader

Note: Some apps like 'Kate' need 'appearances' to be configured in the app same or sometime 'synaptic' don't overtake the Fonts properly. Those issues are very old and as said can be changed in the app same.

Enjoy & best regards.

Hello,
I'm new in this Forum and also no experienced on Devuan (or once Debian). I start with 'Linux Ultimate' (8 years ago), after six months change to 'Ubuntu' and since them stick with KDE (Kubuntu till few months ago and now KDE-Neon). My favorite is KDE 4 but also acclimate (a little bit) with Plamsa 5.

If I well understood for KDE is recommended to use 'ascii' , nevertheless many questions make a round in the head cause of lack of experience in config-files and deep knowledge of Linux in general . I'm mouse-clicker and not programmer but want to joint 'systemd'-free OS and I know that much to learn is on front of me. At end looking for (at least) best links to reach my goal and here the questions/detailed-link-request:

1) Newbie-Link (please) with instructions for install 'Devuan' and switch to 'ascii' (if necessary/recommended).
2) Newbie-Link (please) to set 'OpenRC' as default and parallelize it (parallelized services-start and applications?).
3) Wish to know witch Kubuntu-/KDE-Plasma-Version-s correspond to 'ascii' and the 'PPA' i have to insert.

An additional question is: Will 'Wayland' take place (a day) /come to 'Devuan'?

Thank you very much in advance for any answer and best regards, Terence.

Note: I can abdicate to parallelized 'openrc' if it not work.