A few days ago a friend sent me a link for an Apple II Raspberry Pi emulator.
As far as I can see, it's a linapple emulator, placed in the Raspbian startup sequence, to get faster boot time.
It is a free open source emulator, so you can download, record it on a micro sd card and use it on your raspberry pi if you like.
I tried it on Pi3 and it works without any issues.
It launches directly in DOS 3.3 and from there you can use a large amount of software (mostly games), found on this micro sd card image.
Here's the link: