These are pepinos.
The pepino (Solanum muricatum) is a low-growing shrub in the same plant family as the tomato and the potato. The fruits are usually lemon-sized but can be smaller or larger. The flesh when ripe is pale orange and the flavour is similar to rockmelon, only not as strong. They’re extremely juicy and easy to propagate and grow.
I was given a branch of a pepino plant by a friend a couple of years ago. I cut it into 6 pieces and put them up as cuttings. They grew roots in just over two weeks and eventually I planted them all out. They flower mainly in spring and summer and produce fruits in autumn. The weight of the fruits tends to cause them to lie on the ground where they’re liable to attack by any number of critters, so keeping them up off the soil is advisable. I sat mine on upturned margarine containers.
I’ve also grown them from seed. The seed needs the same conditions as tomatoes, i.e. sow and plant out during the warmer weather. The bushes are perennial, but may have a short lifespan in some soils, so keep new plants coming along. Pruning them back in early spring might also be a good idea.
The pepino hails from South America. It’s a useful addition to the permaculture garden.