Drain the canned fruit very well, then stir together in a serving bowl along with the sour cream substitute, coconut, and mini marshmallows. Chill well. Just before serving, stir in the banana slices, if desired.
This works very well with real sour cream or with Tofutti substitute. It would probably work nicely with plain coconut milk yogurt, as well.
This can be adjusted to be free of most allergens, if you can find a suitable sour cream or substitute and marshmallows. It may not be possible to be free of all allergens at the same time however. For corn free marshmallows, you can make your own or use kosher for Passover options (which would contain fish gelatin and possibly egg white).