hi ,
darkmode (white text/black BG) is more than a design feature, many people with low eye vision need it as accessibility tool, so please include a darkmode “out of the box” toggle (eg by including the propper “High Contrast Inverse” GTK dark theme in the install menu and please also on the welcome tool.
thanks 
This request will need to be implemented by the community. It’s not an area the team will be familiar with.
you mean upstream, by debian ?
yeah that would be ideal, but it should or could be a distro feature to set these things up propper out of the box without tweaks and plugins.
its mind blowing, that in terminal life it always was light text on black screen, but on desktop we switched to white, some distros even use white terminals. fine if a screen is 300nits but on a 1000nits panel black by default would be nice, esp if you have low vision.
What I mean is to work with the team to show what needs to be implemented.
For instance you mentioned a “proper high contrast theme” - I don’t know what this is - but someone needs to create such a theme that is budgie compatible.
You mention a “out of the box toggle” - what does this mean? How would someone needing this find this in the GUI? If this is in budgie-desktop-settings then this work should be worked through via the solus-project github repo. If this is in ubuntu-budgie-welcome then someone will need to help implement this.
This was a default accessibility option until Ubuntu 12.04 or earlier. I can’t answer why the dark option has been removed only leaving users with white.The gnome shell has a dark mode option for the default theme and could have something to do with it. For a work around you could check for black theme @ gnome look.