Yes, that is true. Maybe they want to do something similar in the US? Where they have some subsidiary doing largely independent development for more region specific models?
So it makes sense if VW were to integrate couple Rivian parts into a platform. It won't be a one-side win nor loss.
So that a Golf platform is first developed by VW and then productized by VM and Skoda, but Skoda is already developing next year's platform which VW will use.
Do you have any evidence for Skoda developing a platform on their own?
Audi and Porsche did do their own platform development, but that was never used by VW or Seat or Skoda and was for a completely different market segment.
https://www.autocar.co.uk/car-news/new-cars/skoda-handed-con...
Not developing as in starting from zero, but developing as in taking an existing platform and modifying/improving it for a new series of cars (in this case simplifying the platform to make it cheaper to produce, and targeting the very lowest end of the car market). Admittedly not a platform we're likely to see in 'the west', and sure it's nothing fancy, but I guess you have to start somewhere.
edit: reading back through the original thread, I agree that you are correct that Skoda is not developing a ground up platform that will be the basis for several VAG cars.
And it definitely isn't something which VW uses to base their own cars on.
That seems counter productive though, they seem to want Rivian tech. Usually their brands are managed centrally, so VW is developing platforms and architectures, which are then used by Skoda, Seat and Audio to make their models.