How to Import PDF in Single Column

The only built-in connector is Pdf.Tables, and I do not believe there is any way to prevent it from parsing the PDF content into a table of tables of page text and tables (charts, etc.). You may want to look into using Power Query R or Python.

That said, here is a general set of PQ transformations you can use to convert the default Pdf.Tables parsing into a something similar to Lines.FromBinary, which I think is what you are asking for.

let
    // Load the PDF file a location
    // Note: Use File.Contents for local files
    Source = Web.Contents(
        "https://file-examples.com/storage/feeed4f6296807c3196e058/2017/10/file-example_PDF_1MB.pdf"
    ),
    // Parse the PDF file to extract its content
    PdfParse = Pdf.Tables(Source),
    // Filter the parsed content to get only the pages
    GetPagesOnly = Table.SelectRows(PdfParse, each ([Kind] = "Page")),
    // Combine all the separate tables of page content into one table for the whole file
    CombineAllPageContent = Table.Combine(GetPagesOnly[Data]),
    // Merge all columns into a single column (called "Merged")
    MergeAllPageColumns = Table.CombineColumns(
        CombineAllPageContent,
        Table.ColumnNames(CombineAllPageContent),
        Combiner.CombineTextByDelimiter("", QuoteStyle.None),
        "Merged"
    )
in
    MergeAllPageColumns

Quick visual of the steps to see what the above is doing: