We call them pineapple guava. I have my own tree/bush in the back yard. My grandparents had a tree/bush and I used to eat the guava as a kid. We would cut them in half and spoon out the flesh. I absolutely love them.
Funny you should ask, I saw them when I was out the other day, and I thought I should try them. Not sure why but I left without them however after your comment I shall definitely take them home next time.
No. I saw some feijoa seedlings for sale recently and was thinking of buying one, but decided I need to check whether I like them before I put in years of effort into trying to grow some. Good to hear that they're tasty.