Sadly it was always on the cards. Won in every region except Prague, where he was heavily beaten by the current government coalition. He hasn't got enough for a majority, so he'll need some support from the extreme right smaller parties. Not good news for Ukraine I'm afraid.
Fortunately, he won't have a constitutional majority (even with the support of the extreme parties). This should limit his ability to pass constitutional changes or major legislation without them having broader house support.
The only other crumb of comfort that I can come up with is that the more extreme parties (on the left and right) underperformed expectations by some margin, which shows that the vast majority of Czechs are still very much pro-EU and pro-NATO.