Maybe I can see some use-case for personal use (big maybe), but right off the bat, you can't use this at any company (small startup or enterprise), for several reasons: Lack of functionality, lack of organization-based group and access control workflows, auditing, user provisioning/de-provisioning, lack of cross-organization document sharing and collaboration and compatibility, plugin support, email integration, domain hosting, etc. etc.
I'm not even sure a motivated individual contractor could use this professionally due to the need to collaborate with their customers. I'm not even sure you could dog-food this while managing Nino Inc.
>Nino is one (super)app that supports 18 modules, saving you time from switching and integrating between different providers.
Is that even a real problem?
Most places will use either Microsoft 365 or Google Workspace - those platforms are very well integrated internally. MS365 has all the apps you built except they are feature-rich and some are industry standards (like the Office suite), plus much more - and everything is very well integrated.
But that isn't enough. Sometimes users may prefer, for example, Confluence as a wiki instead of the MS365 Sharepoint wiki - the reason why is because they want to choose a 'best of breed' solution for their use case .. or it may just be a subjective preference. In that case, yes, the integration isn't as great but it is workable (there are plugins to allow deeper integration of external applications). Your solution won't be able to get away from that either. Even if I like your Todo and Notebook apps, I may prefer using Zoom for conference calls and Slack for chat .. what happens then?