There are organizations like https://crfg.org/ that grow exotic fruits that grocers don’t bother to stock. They don’t sell them (not enough money in it), but I know they’ll at least provide you with some if you’re doing an educational thing.

There are also a few businesses following exactly the model you outline, but they focus on one varietal/cultivar of one fruit, since each requires its own CapEx for its own climate setup.

The host of the YouTube channel https://m.youtube.com/c/WeirdExplorer gets fruits in from both of these all the time, (when he’s not going directly to other countries just to try exotic fruits.)