But the most interest thing is that in the process I also wanted to remove my dependency on the other centralized SaaS, so I ended up setting up my own git repository (gitea), my own CI (woodpecker), my own project management tool (Taiga), my own knowledge-base/data sharing tool (Baserow).
On the one hand, I agree with you and think it could be a great business opportunity. On the other, the whole thing is so easy to be completely commoditized that I don't see a practical path to profitability. If I go to investors with the idea, they will say (rightly so) that there is no easy way to establish a competitive advantage. If I bootstrap (like I have been doing with Communick) I can not be fast enough to do both customer acquisitation and development.
That aside, governments have the resources to do this themselves, that's how they currently do so. Extending those services to local organisations would be a step in the right direction.
The thing about services and tooling is that for many orgs, there's not a whole lot you need, and once you're at a scale where you need tooling to manage that scale, you presumably have the resources for an operations team to deal with that, and can outsource the bits you can't do.
The org I work for outsources our public-facing website work to a web-design co, because that's their speciality, and not ours.
All of that is to say; I agree with you, but I think they already exist in the form of SIs.
I'm thinking a portfolio of auth, storage, chat, email, code repository, project management... Everything an organization could in theory host itself but realistically does not have the personnel for.