Pull up a stool 😉
Short answer: If you eat a pineapple immediately after eating a steak? The two meals will be mixed together. The mixed meal will move slower than if you had only eaten a pineapple, and it will move faster than if you only ate a steak.
Long answer: Steak is predominantly protein and fat so it is more fully digested compared to pineapple, which is predominately fiber, water, sugar (fiber not being digested).
Pineapple will actually move faster along the digestive tract, since water and sugar are rapidly absorbed. The fiber content also helps to move things along quickly.
A steak moves slowly in the digestive tract because it takes time to breakdown the fat and protein. Once broken down, the absorption of protein and fat are more complicated than sugar and water.
TLDR: Most of the pineapple will be digested first. You will poop it all out at the same time.