Thank you for starting this thread! All properties that comprise the CSS Grid standard are supported in Bootstrap Studio. This means that you can drag/drop some divs, write some CSS and get a grid layout.
What we don't have, though, is visual tools for CSS grid. We try no to deviate too far from Bootstrap, but if CSS gains traction we can add support for it. It will be a separate thing from the Bootstrap grid with its own set of components.