Interesting. I wasn’t aware of Kolab.
I reckon the first company to provide a viable G Suite alternative that is easy to migrate to will have a huge market opportunity. Beyond individual privacy enthusiasts and activists, I can see the ethical software approach being appealing to governments, educational institutions, and scientific organizations.
Businesses too to some extent, but I know that most just want to get things done quickly and easily, and so it will be hard for them to be convinced to give up the likes of G Suite just based on principle. Time is money, and so any downtime due to migration or retraining staff will cost them.
As for why Purism hasn’t gone with a provider like Kolab, perhaps they prefer to cherry pick individual apps so that if something goes wrong with the core project, then they can swap it out for something else. Whereas, if the consolidate with a provider of a full suite, then if that goes bad, they are more vulnerable. A strategy of diversification, perhaps.