well this a question regarding the possibilities od a specific (game) render engine… i suggest looking into to docu of (here) Unity or the some specialized forum like so:
This was more a suggestion to use the docs or the forum of unity… i’m sure there must be a section about applying multiple material on on object… or the pros and cons about using it… like so:
Do 6 x 4. That is the topological equivalent of a cube with level 1 subdivision. So its easier to break up for mapping. But of course subdivide it far more.
Must it be a single object in Unity? Why not break it up into a 1/4 of each of the 6 sides? That is as close as you can get to a nice square UV layout. So 24 materials.
Stick them all onto a solid sphere if needed. Never used Unity so I dont know what physics or material limits there are.