Map Content Type in Copy Structure
It isn't possible to map content types during a whole site migration. Is this something that we want to look into?
Fred Larssen commented
Definitely. Both content types and properties.
Have a look here: https://feedback.sharegate.com/forums/912880-sharegate-desktop-suggestions/suggestions/16437697-map-property-on-a-site-object-migration
Voted for this one as I came across this problem when migrating sites with lots of sub-site content. Though I've still achieved what I wanted with site columns being available to the search experience and use refiners in classic mode.
Thanks to James McClymont for highlighting this suggestion.