Ridiculous concept of clinging to 'the pure line'
But to answer:
Dutch: I don't know if even a purist could find one to exist. The last prince born before WA was his namesake,Queen Wilhemina's older half brother who was born in the 1850's. Queen Wilhemina's three brothers died without heirs before their father. William II (her grandfather) only had one son who had children, William III. William I had two sons who had children, but his other son Frederick had only had 2 sons and they both died in childhood. You'd have to go back to the Princes of Orange, before there was a king of the Netherlands,to determine if there was an unbroken male line to follow. Maybe someone who actually cares about this agnatic mentality would actually bother to go further, I don't.
British: have had more than one reigning queen, so question how far back would we need to go. The male line certainly been broken many times. The most recent would be simple enough. If agnatic, instead of Elizabeth being queen, the throne would have passed to her uncle Henry, Duke of Gloucester. When he died the current Duke of Gloucester with Alexander as Prince of Wales and his son Xan after him. But then again George V is descended from Victoria, so if Elizabeth shouldn't have been queen, either should have Victoria. If Victoria had not been queen, the throne would have followed the same path as the other family titles. The Hannoverian titles could not be inherited by a woman so were inherited instead by Victoria's Uncle Ernest Augustus. The throne would have passed the same. It would mean Prince Ernst August (husband of Caroline of Monaco) would be king of the UK,and his eldest son Prince Ernst August would be Prince of Wales. But then again the Hannoverians only came to the throne due to the female line. So honestly who knows?? better question who cares???
Denmark: The throne would have passed to Prince Knud of Denmark instead of his niece Margrethe. The problem is both Knud's sons lost their place in succession,only his daughter retained their titles. If their father had been king, it is quite possible the marriages would have been approved by their father to maintain their place in succession. Count Ignolff would have been king after his father, but he has no children. And his brother Christian only has daughters. You would have to back a generation,to the brothers of Christian X (father of Knud and Margrethe's father). The next brother was King Haakon of Norway. Meaning the direct male line would bring us to Haakon and Sverre Magnus.