XFCE 4.20, Wayland (labwc), GDM, Linux Lite 7.x
Test Continuation
Most system themes for Wayland remain incomplete though KDE and Gnome are getting more and more feature mature. Testing Wayland in Linux Lite 7.x I uncovered a few shortcomings and missing application options with onboard themes. In the image below I am running the materia-dark theme with papirus icons. The Thunar Preferences window is too large for the display and unfortunately cannot be resized in Linux Lite 7.x running Wayland, a common problem with Wayland in general.
However running the greybird-dark theme shows the window fitted properly in the display.
It also displays correctly sized with the regular greybird theme.
I also noticed even after trying several different dark themes and icon sets including all the yaru (Ubuntu font and theme) versions, that no color icons could be obtained with any dark theme I tried in LibreOffice under Wayland.
Laudably the included Linux Lite 7.x default theme greybird produced colored icons for LibreOffice running in Wayland.
After testing quite a bit more with various currently available themes and icon sets greybird certainly seems to be the most mature theme to run in Wayland labwc on Linux Lite 7.x. I also expect that greybird-dark will probably be the first to solve the issues with icon sets and dark themes in LibreOffice under Wayland. Between systemd and Wayland Linux development has endured a frenetic schedule of change in the last 20 years, but it still keeps getting better and more capable.