Yaru MATE is the default GTK theme for Ubuntu MATE 21.04 and newer.
snap install gtk-theme-yaru-mate
snap install icon-theme-yaru-mate
To connect the theme to a snapped application, you can run:
sudo snap connect [other snap]:gtk-3-themes gtk-theme-yaru-mate:gtk-3-themes
sudo snap connect [other snap]:gtk-2-themes gtk-theme-yaru-mate:gtk-2-themes
sudo snap connect [other snap]:icon-themes icon-theme-yaru-mate:icon-themes
Or, you can connect the Yaru MATE snapped theme to all snapped apps that support theme plugs:
for PLUG in $(snap connections | grep gtk-common-themes:gtk-3-themes | awk '{print $2}'); do sudo snap connect ${PLUG} gtk-theme-yaru-mate:gtk-3-themes; done
for PLUG in $(snap connections | grep gtk-common-themes:gtk-2-themes | awk '{print $2}'); do sudo snap connect ${PLUG} gtk-theme-yaru-mate:gtk-2-themes; done
for PLUG in $(snap connections | grep gtk-common-themes:icon-themes | awk '{print $2}'); do sudo snap connect ${PLUG} icon-theme-yaru-mate:icon-themes; done
An official snap built with ❤︎ by the Ubuntu MATE team using configuration at https://github.com/ubuntu-mate/gtk-theme-yaru-mate-snap and the Yaru theme from the upstream project source https://github.com/ubuntu/yaru.