CREATE FUNCTION dbo.GenericStringAgg (
    @tableName NVARCHAR(MAX),
    @columnName NVARCHAR(MAX),
    @groupColumn NVARCHAR(MAX),
    @groupValue NVARCHAR(MAX)
) RETURNS NVARCHAR(MAX)
AS
BEGIN
    DECLARE @sql NVARCHAR(MAX);
    DECLARE @result NVARCHAR(MAX);

    SET @sql = N'SELECT @result = STUFF((
                    SELECT '','' + ' + @columnName + '
                    FROM ' + @tableName + '
                    WHERE ' + @groupColumn + ' = ''' + @groupValue + '''
                    FOR XML PATH(''''), TYPE
                ).value(''.'', ''NVARCHAR(MAX)''), 1, 2, '''')';

    EXEC sp_executesql @sql, N'@result NVARCHAR(MAX) OUTPUT', @result OUTPUT;

    RETURN @result;
END