Phone's are not that UnderPowered. this is not 2000's.
There are already apps like this one for Android, search, aneko, shimeji, virtual pet buddy to name a few so, it is possible, maybe not with all the features of the desktop version, but still.
Also, do you know? Android doesn't have RAM since it's an OS (software) the device itself is the one with the RAM ( hardware) and it varies from device to device :)