Solution: I found some workaround to this „feature“ to achieve exact path offset is through duplicating the object, then playing with its stroke parameters, and later converting stroke to path.
Step 1. Make a duplicate of your original object (that is already a path object).
Step 2. Make a stroke of desired width, and remove fill of object. You can again make another duplicate of the same path and adjust its transparency, then set stroke of another for a better view of stroke width. Also set stroke style to „Miter join“ and adjust values.
Step 3. Convert stroke to a path object.
Step 4. Make a another copy of original path. If you want a bigger offset of original, then align stroke object and one of the originals as you want, then path union both objects. If you want a smaller offset of original, then align stroke object and one of the originals as you want, then make a path difference.