With this command I get an empty file.
user@Debian-Sid-i3:/$ dconf dump /org/onboard/ > /tmp/test.conf user@Debian-Sid-i3:/$ cat /tmp/test.conf [/] current-settings-page=5 layout='/usr/share/onboard/layouts/Small.onboard' schema-version='2.3' show-status-icon=true start-minimized=true system-theme-associations={'HighContrast': 'HighContrast', 'HighContrastInverse': 'HighContrastInverse', 'LowContrast': 'LowContrast', 'ContrastHighInverse': 'HighContrastInverse', 'Default': '', 'Adwaita-dark': '/usr/share/onboard/themes/Nightshade.theme'} theme='/usr/share/onboard/themes/Nightshade.theme' use-system-defaults=false xembed-onboard=true [icon-palette] in-use=true window-handles='E SE S SW W NW N NE M' [icon-palette/landscape] x=1959 y=1002 [keyboard] audio-feedback-enabled=false show-click-buttons=true touch-feedback-enabled=false [theme-settings] background-gradient=0.0 color-scheme='/usr/share/onboard/themes/Charcoal.colors' key-fill-gradient=8.0 key-gradient-direction=-3.0 key-label-font='' key-shadow-size=0.0 key-shadow-strength=0.0 key-size=94.0 key-stroke-gradient=8.0 key-stroke-width=0.0 key-style='gradient' roundrect-radius=20.0 [typing-assistance/word-suggestions] enabled=false [window] docking-enabled=true docking-monitor='active' docking-shrink-workarea=false enable-inactive-transparency=true inactive-transparency=50.0 transparent-background=true window-decoration=false window-handles='' window-state-sticky=true [window/landscape] dock-height=351 height=491 width=2120 x=16 y=565 [window/portrait] dock-expand=true