Sorry if this was mentioned before, there was an old PC game called Operation based on the board game of the same name and in my experience, they gave it away for free in cereal boxes (alongside other titles such as Monopoly, Rollercoaster tycoon, Yathzee, etc.). The game played much like the board game but instead of removing objects from a patient, you could access mini games to cure them.
The dinosaur mini game had the caveman doctor tied a rope around himself and lowered himself inside the stomach of dinosaurs. There is no animation of the doctor tying the rope or being swallowed, you just click on some kind of extinguisher and it transition to the stomach. The goal was to shoot puffs of smoke on acid bubbles. If I recall correctly, if you win or fail, the stomach rumbles loudly and the rope pulls the doctor out. You can't be digested.
The monster mini game was activated by clicking on a tongue depressor. The player controls a frog inside the throat of the monster and you have to climb up the esophagus. The mad doctor throws all kind of stuff inside the monster's mouth for some reason and you have to evade the objects sliding down. When you reach the back of the tongue, the frog wrap its tongue around the uvula and jumps outside the mouth. Weirdly enough, the mouth is human-like. If you fail, the frog falls down, there's no swallowing sounds. The inside throat shot is also the picture shown at the end credits.
The human mini game have the player control some green cowboy lice jumping on a human body and the goal is to fall on top of the enemy lice to same-size swallow them whole. They will eat you if they fall on top of you. I forgot what the other two mini games were about, one was in the jungle with animals and the other was in a space station with aliens. I'll assume they weren't vorish or I would have remembered them, but I could be wrong.
This is the game:
https://youtu.be/cHc4WvxMna0