AngleSharp by Florian Rappl

<PackageReference Include="AngleSharp" Version="0.6.0" />

.NET API 844,288 bytes

 IText

The Text interface represents the textual content of Element or Attr. If an element has no markup within its content, it has a single child implementing Text that contains the element's text. However, if the element contains markup, it is parsed into information items and Text nodes that form its children.
string Text { get; }

Gets a string containing the text of all Text nodes logically adjacent to this Node, concatenated in document order.

IText Split(int offset)

Breaks the node into two nodes at a specified offset.