short answer: when it's done
long answer: I have attempted to start a port to WidgetKit (and/or porting the base app to SwiftUI) about five times now, and until very recently I couldn't get SwiftUI previews (required for WidgetKit) to work at all on my machine, with mysterious unsearchable errors every single time
I want @Watch to be on as many Apple platforms as I can get thru App Store Review for, I want it on my Mac, I want it on my iPhone Lock Screen, I want a widget, I want a complication, I want a menu bar extra, but the migration from ClockKit to WidgetKit is kinda non-trivial AFAICT and given it took me nearly a year to get through App Store Review the first time on top of getting it to update reliably there is some hesitation to put myself through that emotional turmoil again
honestly if anyone is experienced and would be up for helping me port the complications uhhh? hit me up, name your terms
but know that I want it just as much as you do
(p.s. does it still work on watchOS 10 as a normal complication? I haven't been game to install a developer beta yet)