Tips:

• Perform "Merge by Distance" ("M" > "By Distance" in Edit Mode) operation before unwrapping, if possible. Due to algorithm's logic, it will mark all open edges (mesh boundaries) as seams, in order to "attach" seams to mesh borders.
• On dense geometry, increase the "Seam Margin Amount" value, to avoid several seams close by.

Operators Descriptions:

Unwrap

Unwraps all selected objects and all meshes within them, using specified settings.

Unwrap Steps

Unwrap iteration step, rough maximum of seams. If result doesn't produce enough seams, increase this value. Ranges from 1 to 250+.

Curvature Threshold

Cut off of curvature values that won't be considered. 0.01 is almost flat geometry, 1 is a perfectly sharp angle. Higher the number - sharper features will be marked as seams. Generally, more high poly the model - lower this value should be. Ranges from 0.01 to 1.

Extend Amount

Max length of each seam loop in edges, generally around 500 will produce good results, tweak this value if a lot of noise is present, or if seam loops stop short for no apparent reason. Ranges from 0 to 1000+.

Seam Margin Amount

Amount of margin every seam has, to avoid several seam loops close by. More generally is better on dense geometry. If your low poly geo doesn't have enough seams - this value may be too high. Ranges from 1 to 10+.

Seam Search Radius

Radius in which seam loop will try to find other seams to connect with. Higher - more closely joined seams. Ranges from 1 to 5+.

Overwrite Seams

Option to overwrite existing seams. If unchecked - OKUnwrap will add seams to already existing ones.

UV Unwrap

Will unwrap the model after seam generation. If unchecked - OKUnwrap will only add seams to the model.

Curvature Bias

Affects how much the curvature of the mesh will affect the seam loops. Higher the value - the more seams will adhere to sharp (both convex and concave) features. Ranges from 0 to 1+.

Inline Loopness Bias

Affects how much the seam loops will try to run straight. Ranges from 0 to 1+.

Seam Closeness Bias

Affects how much the seam loops will try to connect with already existing seams. Ranges from 0 to 1+.