My daughter is the same.
Carrot, cucumber, avocado, cream cheese, fish. I've used traditional fish, but also smoked salmon and even fish sticks. Makes it cheap and easy and she doesn't care.
You don't need sushi vinegar in my opinion. I've used whatever is on hand for the vinegar, sugar, salt. Apple cider, white - don't overthink it.
Hell, I don't even use the rolling mat, anymore.