Bandai has updated their 30 Minute Missions site with a back story. Of course builders are free to write their own. But if they want to follow something, here is an option. This is more like themed Lego where they give you a template but you could still freely work out scenarios with them. So in short, not geberal purpose Lego, but theme Lego with no storyline/plot but only a premise.
https://bandai-hobby.net/site/30minutes_missions/sp/story_sp.htmlAfter a few decades of the event known as Skyfall in which a portal opened up on Earth's orbit, various nations on Earth were still at war with one another with the introduction of a new type of weapon "Examacs" which has modernised warfare.
At the end of 2XXX, a portal appears for a second time with a robot army from Planet Byron attacking all regions around Earth using Examacs-like machines called Portanova.
The nations who were already at war with one another banded together to form the Earth Alliance to repel the forces of Byron.
eEXM-17 Alto
Third generation machine.
A machine belonging to the Earth Alliance developed by IT Corporation Sylas. It is a standard machine that boasts mobility and usability. Various regions have their own colour schemes and equipment.
bEXM-15 Portanova
Third generation machine.
Machine used by Byron that focuses on armor resistance and power output. Its armor was designed to resist well against both solid rounds and beams. The high output of this machine was intended for beam weapons usage. In the Byron homeworld, units such as the Black Guards Division are known to exist.
Obviously, this is just a template. Maybe they will give us sample squads to work with as well. It seems like they want to give us the idea thst colours could represent regions/factions for Earth and different divisions for Byron.