For that, there's https://valetudo.cloud/ that supports a number of models from different brands.
The dev opposes selling the connector PCBs, but people have always ignored that and sold them online. They're not hard to find, but having the PCB is really only the first step.
Not banning people that want to buy a flashing kit instead of making one would be a start.
I for one would learn nothing, and wanting privacy shouldn't require an arbitrary skill when unnecessary like in this case. Not even mentioning that buying the parts is prohibitively expensive compared to some finished kits I've seen.
https://valetudo.cloud/pages/general/supported-robots/#eurek...
I did this, it's as easy as it is described. Fully functioning robot vacuum free from the cloud.