They explicitly call out in the mod tools announcement on Steam that level editing will NOT be supported.
For cross-platform support, direct level editing and changes to core game elements (like story, cinematics, dialogues, quests, and local gameplay adjustments) can’t be facilitated due to technical constraints and platform-specific guidelines.
And that there's plenty of people perfectly willing to create cool stuff without any expectation of making money from it but just because they like creating and sharing their creations for others to enjoy.