Hello,
Factorio version 2.1 features a button to hide unresearched content in Factoriopedia. I think this could be forced on for Ultracube so players can still get an overview over what they can do with their current unlocks without spoiling unresearched content, which I guess is the reason for Ultracube not allowing the usage of Factoriopedia at this moment.

A strong +1 to this one. Playing mods without factoriopedia (or similar mods) is a huge pain, as the only way to know the uses of any item is manually scanning the tech tree (and even then you might miss something).
I use https://mods.factorio.com/mod/RecipeBook with show hidden + hide unresearched options so it correctly shows only the known recipes, but that is not getting upgraded to 2.1 so I'm waiting on 2.0 for the moment.