Like Frames, Figma's Groups will get mapped to Stacks. The only difference is that in Figma Groups, constraints get applied to the elements inside rather than to the Frame. Therefore, applying constraints to a Group is essentially applying constraints to every item inside the Group.
Take the following Figma Screenshot:
The vertical constraints are Scale, while the horizontal constraints are Pin Left. The following code is generated by Parabeac:
As seen above, the Scale causes the vertical attributes (top and height) to use MediaQuery in order to be dynamic. The horizontal scales (right, width), however, are fixed since they are pinned.
For more information on how constraints are generated inside stacks, see: