internal/functions/ConvertTo-MarkdownLine.ps1

function ConvertTo-MarkdownLine {
<#
    .SYNOPSIS
        Converts an input html paragraph to a markdown line of text.
     
    .DESCRIPTION
        Converts an input html paragraph to a markdown line of text.
     
    .PARAMETER Line
        The line of text to convert.
     
    .EXAMPLE
        PS C:\> ConvertTo-MarkdownLine -Line $Line
     
        Converts the HTML $Line to markdown
#>

    [CmdletBinding()]
    param (
        [Parameter(ValueFromPipeline = $true, Mandatory = $true)]
        [AllowEmptyString()]
        [string[]]
        $Line
    )
    
    begin {
        $mapping = @{
            '</{0,1}em>'     = '_'
            '</{0,1}i>'         = '_'
            '</{0,1}strong>' = '**'
            '</{0,1}b>'         = '**'
            '<br>'             = '<br />'
            '<span style="font-weight: 400">(.+?)</span>' = '$1'
        }
    }
    process {
        foreach ($string in $Line) {
            foreach ($pair in $mapping.GetEnumerator()) {
                $string = $string -replace $pair.Key, $pair.Value
            }
            ($string -replace '</{0,1}p.{0,}?>').Trim()
        }
    }
}