Okay, I discovered this by accident. It’s how to play the full Banjo game from the trial.

Step 1: Get into Spiral Mountain
Step 2: Go to the giant Ape and make him hit all 3 orange tiles. Make sure the one furtherest away from the tree stub with the monkey is hit LAST. DON’T GET THIS JIGGY YET.
Step 3: Get the orange from Ape’s tree, and give it to the monkey on the tree stub. GET THIS JIGGY.
Step 4: Go to the mole hill above the tree stump, learn how to egg attack, and beat the Ape. A Jiggy will fall.
Step 5: If done correctly, the 2 Jiggys will be right next to each other. Jump right in the middle of them. You should collect 2 Jiggys at the same time, extending the trial.

TRY IT OUT. The only thing you can’t do is save.