Had a go at creating a Nanite model for Unreal Engine. A medieval cannon seemed like a good test subject, with its variety of small, organic, intricate details. Final in game model was 1.4mil tris, which I'd guess is probably a bit overkill for a model like this. If I redid this for an actual production Nanite game asset I'd guess I could and would have authored it much lower - maybe 250k tris. Maybe lower, who knows. I'm just guessing at this point. But, I kind of wanted to push the limits a little bit and see what's possible and get a feel for the process. And make a 1.4 million triangle game model just cuz I can :)
Also, this is a unique, 1:1 texture set. At this level of mesh density/detail, I think I could probably ditch the unique textures (diffuse/normal, RMO) and just use a layered material/tiling textures workflow with RGB masks for material definitions and wear and grime etc, which might be an effective alternative. Less texture maps balancing out the additional geo. Would be a neat experiment - maybe some day...
Cannon was my own design. Rendered in Unreal 5 with Megascan background/environment assets. Ornate trims from Artstation marketplace - Jonas Ronnegard and AMcg - not sure whose I wound up using -