You're right, she's not ready to go through the night.
Diapers aren't her choice -- it's your decision. She's probably heard people talking about "big girl" underwear and she wants to be like them - but 2.5 is way too young for the vast majority of kids.
You could try a very small size of something like "good nights" and show her the picture of the big kids on the package. You could try a pull up with those extra pads/liners that go inside. Again, show her the big kids on the package. Tell her this is what kids wear to bed. I'm concerned though, because she is SO young, that everything will be too big for her.
This is not something in her control at all. A lot of kids are 5 or 6 before they are reliably dry at night.
You're going to have to be the parent here no matter how hard she fights you. It stinks, I know. But her sleep is more important, and she's getting interrupted by lying in a bed of pee and having all the commotion of changing pajamas instead of just falling back to sleep. Her brain really really needs this time - so please don't give in to her no matter how much she screams.
She has to get away from the idea of "training" - this is nothing you can train kids to do. They grow into that developmental stage naturally - just as they start to walk or talk at different ages.