PDFsharp & MigraDoc Foundation

        var document = new Document();
        SetupStyles(document);
        var section = document.AddSection();
        section.PageSetup = document.DefaultPageSetup.Clone();
        section.PageSetup.PageFormat = PageFormat.A4;
        section.PageSetup.LeftMargin = section.PageSetup.RightMargin = Unit.FromCentimeter(1);
        var table = section.AddTable();
        table.Style = StyleNames.Normal;
        table.Format.Alignment = ParagraphAlignment.Center;
        table.Borders.Top.Style = table.Borders.Bottom.Style = table.Borders.Left.Style = table.Borders.Right.Style = BorderStyle.Single;
        table.Borders.Top.Width = table.Borders.Bottom.Width = table.Borders.Left.Width = table.Borders.Right.Width = Unit.FromPoint(4);

        Color[] colors = new Color[] { Colors.LightGreen, Colors.LightSalmon, Colors.LightGray, Colors.LightBlue };
        int color_index = 0;
        var width = section.PageSetup.PageWidth - (section.PageSetup.LeftMargin + section.PageSetup.RightMargin);
        for (int c = 0; c < 10; c++)
        {
            table.AddColumn(width / 10);
        }

        for (int rowIndex = 0; rowIndex < 10; rowIndex++)
        {
            var row = table.AddRow();
            for (int cellIndex = 0; cellIndex < 10; cellIndex++)
            {
                var color = colors[color_index]; //Give each cell its own border color
                row.Cells[cellIndex].Borders.Top.Color = color;
                row.Cells[cellIndex].Borders.Bottom.Color = color;
                row.Cells[cellIndex].Borders.Left.Color = color;
                row.Cells[cellIndex].Borders.Right.Color = color;
                row.Cells[cellIndex].AddParagraph($"{rowIndex},{cellIndex}");
                color_index++;
                if (color_index > 3)
                    color_index = 0;
            }
        }

        return document;

DocumentRenderer renderer = new DocumentRenderer(document); //MigraDoc Document created from somewhere else.
renderer.PrepareDocument();

PdfDocument pdf = new PdfDocument();
var pages = renderer.FormattedDocument!.PageCount;
for (int i = 1; i <= pages; i++)
{
    var page = pdf.AddPage();
    var gfx = XGraphics.FromPdfPage(page);
    renderer.RenderPage(gfx, i);
    var renderInfos = renderer.GetRenderInfoFromPage(i) ?? Array.Empty<RenderInfo>();
    renderer.PrepareDocument();
    foreach (var tableRenderInfo in renderInfos.OfType<TableRenderInfo>())
    {
        if (tableRenderInfo.DocumentObject is Table table && tableRenderInfo.FormatInfo is TableFormatInfo tableFormatInfo && tableFormatInfo.FormattedCells is not null)
        {
            var y = tableRenderInfo.LayoutInfo.ContentArea.Y.Point;
            XColor[] colors = new XColor[] { XColors.Blue, XColors.Red };
            int color_index = 0;

            foreach (Row row in table.Rows)
            {
                if (row.Index == 0)
                {
                    y += row.Borders.Top.Width.Point / 2; //move Y point into middle of Row's top Border
                }
                //Calculate the maximum inner height from all the cells in the row
                //Cant just look at the first cell, because of how the cell's inner heights are calculated
                double row_max_inner_height = 0;
                foreach (Cell cell in row.Cells)
                {
                    var formattedCell = tableFormatInfo.FormattedCells[cell];
                    var innerHeight = formattedCell.GetInnerHeight().Point;
                    row_max_inner_height = Math.Max(innerHeight, row_max_inner_height);
                }
                var x = tableRenderInfo.LayoutInfo.ContentArea.X.Point;

                double new_y = y + (row.Borders.Top.Width.Point / 2) + row_max_inner_height + (row.Borders.Bottom.Width.Point / 2);

                foreach (Cell cell in row.Cells)
                {
                    if (cell.Column.Index == 0)
                    {
                        x += cell.Borders.Left.Width.Point / 2; //move X point into middle of Cell's left border
                    }
                    double inner_width = tableFormatInfo.FormattedCells[cell].GetInnerWidth().Point;


                    XPoint top_left = new XPoint(x, y);
                    x += (cell.Borders.Left.Width.Point / 2) + inner_width + (cell.Borders.Right.Width.Point / 2); //moves X to middle of next Cell's left border
                    XPoint bottom_right = new XPoint(x, new_y);

                    var pen = new XPen(colors[color_index], 2);
                    gfx.DrawRectangle(pen, new XRect(top_left, bottom_right)); // Just for testing, draw a new Rectangle around each cell
                    color_index++;
                    if (color_index > 1)
                        color_index = 0;
                }
                y = new_y;
            }
        }
    }
}