I’ve only tipped my toes into Scaler 2, but I have yet to figure out how to do the following;
Most often I already got a nice chord progression for a verse (or chorus), but I want to use Scaler to suggest good progressions which can be used for the chorus (or verse) which “fits” the ones I already have.
What is the best way to use Scaler for this usage?
DavidE’s video on using Scaler to provide chords
to a starting melody follows along the same lines
as what you are asking.
I guess, with some development, it could give you list of progressions in the same mode and transpose it to same key. Or, it could give a list of all progressions in the same mode and all keys + simple transition chord(s). At this point of time, Scaler does not do it and you have to “click and explore”.
That, on the other hand, would require a dedicated nuclear power plant and pretty advanced AI 
as there is no mathematical model for “fits”.