The pineapple adds moisture, and it’s not all that noticeable in the finished cake, unless you have large chunks of it. Sometimes I can get get Dole brand crushed pineapple on sale in the supermarket cheaper than I can get it from my distributor and I’ve noticed that it has larger chunks so I will run it through the food processor after I drain it. I have made it without the nuts, and without the coconut but not without the pineapple. Without the nuts is not so bad; I’ve added more coconut to help with the structure when I do that.
You’d need something with a similar consistency - applesauce maybe? But I am not sure how that will affect the taste of the cake, it’s worth making a small batch and testing it to see.