The model and textures are  from 3D Scan Store:  https://www.3dscanstore.com/hand-3d-model/female-hands

First, I removed unwanted shadows from the diffuse texture between the fingers and created some extra maps for shading (cavity, thickness, mask for nails, micro detail map).

Maps:

Diffuse Color

Displacement

Normal

Specular Amount

Specular Amount and Epidermis Subsurface Amount (Cavity)

Epidermis Subsurface Max Depth (Thickness)

Mask for nails

Micro Detail

I projected the micro detail map with solid projection on the model and masked off the nails with group mask.

Shader tree

I used Color Correct and Color Gamma channel modifiers on the diffuse color texture to create epidermis/dermis/lower dermis color variations.

Nodes in Schematic Viewport

Epidermis Subsurface Color

Upper Dermis Subsurface Color

Lower Dermis Subsurface Color

Thank you for reading.