This post will explore how openly and inclusively concepts of
love and sexual attraction are depicted in the manga. While the nations don’t
have canonically assigned sexual orientations—of course, with the exception of Sweden—
it’s the fact that there is a representation of diversity within the series
that matters. Obviously, the term ‘Sexualities’ in the title is used very loosely
for lack of a better word.

In no way will these be all examples included in the manga, but this
should provide a good scope for understanding how Hetalia approaches human sexuality
and the capacity to love.

England: 

England is once described by France as being aroused by anything [x].

Germany:

In the infamous Buon San Valentino strips, a series of
mishaps occur where Germany misinterprets his relationship with Italy to be a
romantic one and proposes to him (really???).
Regardless of the misunderstanding, what matters is that Germany was okay with
the idea of entering a same-sex relationship [x]. Not only that, but he had totally committed himself to it.

France: 

In a volume 2 character note, France is said to go for “guys
and girls of all types”, including non-humans “as long as they’re beautiful.”

In the 2007 April Fools’ event, we also learn that he may
have a preference for “macho men.”

Italy Brothers: 

Both are notorious for being girl-lovers, without a
question. It’s part of the Italian stereotype [x] [x].

On the other hand…

Italy admits to Germany in Buon San Valentino that his first
love was a guy, presumably referring to Holy Rome [x].

In a Volume 2 character note, it’s left open-ended on
whether Romano has a taste for men.

Bonus:

Spain quasi-proposes to Romano when gay marriage is legalized in his country [x].

Sweden: 

Sweden remains as the only aph character to possess a canon
sexuality. He’s homosexual, but only feels this way toward Finland. It’s
one-sided, as Finland doesn’t reciprocate this sentiment [x].

Taiwan:

Strips have suggested that Taiwan may be attracted to women.

In the Christmas 2011 event, she’s unable to concentrate due
to the exposure of other female nations’ cleavage.

In the Halloween 2013-2014 event, she checks out other
female nations.