Albert Lortzing, Zar und Zimmermann (1837)

According to wikipedia, this should be considered, not as you'd automatically assume a Singspiel, but rather a "Spieloper," which is like a Singspiel only comic--to me, it seems like that's just a word for an early German operetta, but it's nice to know!  I suppose.

"Zimmermann" just means "carpenter" in German.  I never knew that!  This is based on the historical thing where Peter the Great disguised himself as a carpenter to study abroad.  Meyerbeer's L'étoile du nord is based on the same incident, but that takes place in Finland, whereas this is in Holland, where the real Peter actually went.  Both of these operas present it as him being in disguise and no one knowing who he was, which is kind of an irresistible idea, but per this reddit post, not at all true: he was trying to be as anonymous as possible so as not to have to deal with all the usual pomp and circumstance, but everyone knew who he was, not least because of his huge retinue.

Well, anyway, here, in the town of Saardam, there's Peter-the-Secret-Czar and also Peter Ivanov, another Russian working in Holland after having deserted from the Russian army.  He and Marie are in love, but her pompous, bungling burgomaster uncle is getting in the way.  There's also various intrigue--that gets a bit confusing in places--with French and English ambassadors who are there to make some sort of deal with Russia, though this is very vague.  Well, hijinx occur, Peter I and Marie are united (the deserting thing is cool, it seems), and Peter t.G. reveals his identity and sails off, and bob's yer uncle.

It's a lot of fun.  The plot gets a bit slack in places--a lot of bumbling around--but hey, opera.  The Rossini-esque music is quite good.  This is a filmed version from 1969, and it starts with a disclaimer that this is one of the first filmed operas in color and we've done our best to restore it but there may still be some small issues.  But if they hadn't included that, I wouldn't have found anything to complain about; there may be a few tiny, blink-and-you'll-miss-it visual artifacts, but in general it looks and sounds quite good.  Would recommend to kids of all ages.