This one, filled with geraniums surrounding Michelangelo's Pieta, is in Cannaregio.
This is a strange one. The reliefs on the tabernacle seem to have some age on them, and that face on the wall above looks exactly like the gatekeeper in The Wizard of Oz. :)
It's very rare to see a shrine that's been vandalized but this one has a busted window. Perhaps the vandal is responsible for the lurid orange color of Baby Jesus' face? It's a bizarre image inside!
This oratorio is listed on the Patriarch of Venice website which says that it has two small rooms inside. Built in 1829 by workers from the Arsenal and dedicated to Beata Vergine Addolorato (Our Lady of Sorrows). Restored in 1995. I've never found it open. It hardly looks big enough to have two rooms.
And this one is in Castello, in Campiello del Figareto, and it isn't on the oratory list so I guess it's a shrine and/or private chapel. There's a Madonna and Child inside that you can barely see and I couldn't photograph because it's so dark in there. The inscription says that it was built in 1842, restored in 1979. In the second photo, you can see where someone has stuck a single long-stemmed rose in the grate of the door.