When selecting an item and swiping/flicking right or left with one finger, VoiceOver should select the next or previous item and don't go out of the chat history when reaching the limit of the visible area.
You can use the touch on the corner of the screen to slide the conversation up or down. (It's an issue already reported, see the related issue). This workaround can cause the chat to scroll many messages up/down, causing the user to get lost in Chat.
With VoiceOver enabled:
A message in chat history or a chat in the chat list
VoiceOver reads one or two messages and starts to go through the options around the chat: Focus is moved out of the chat history / chat list.
Next/previous item in the chat history / chat list is selected by swiping right or left, no matter if it's out of the visible area.