Are you referring to smoothing groups by UV shells?
Actually it's the other way round - UV has to have seams where there's hard edges on the low-poly model. You don't make hard edge just because there's UV seam, you make them because you want better control over smoothing and less stress on normal map.
Marmoset has option to bake in 3ds Max tangent space, but no support for UDIM; tradeoffs
You don't need Marmoset to bake normal map in specific tangent space, you just need that your app would be able to bake object space normal map and then use Handplane to convert normal map to whatever space you need. I used Marmoset just because it has much more convenient (and at that time faster) baker than Painter.