Fine tuned models for summarisation?

I have a db with a lot of data that all need precise summarisation, I would do it myself if it wasn't 20 thousand fields long

It is about 300k tokens, and Gemini 2.5 struggles missing points and making up facts

Separating them into smaller sections is not an option, because even when seperated they can take up 30k tokens, and the info that needs summarisation may span 100k token ranges

I learnt that fine tuning may have better results than general purpose models, and now I'm wondering if there is anything high token count for summarisation.

Any help would be appreciated, even if its to suggest another general purpose model that has better coherency