I’m just presenting that as a “is this what you mean”. If it is, then perhaps a FOSS or self hostable version fists or the community might be interested in one existing.

It’s not self hostable, but you mean something like this? https://calendarbudget.com/

I played a bit with the basic concept of identifying and categorizing merchants by importing a transaction csv into google sheets and writing a custom function that called the OpenAI API, basically just passing the raw merchant string along with “What category of business is this?”. It did well, the next step would have been to add a step that compared to a predefined list of possible categories. I didn’t compare any models or other platforms though. This was last year so I might play with it again.