I too think your definition of MVP needs to be adjusted. It sounds to me like an excited user came up with the MVP feature list, not an experienced developer, like "it's gotta have rich text editing capability and pdf export and offline support and nice ui!" because how can you not highlight important notes in bold and download your notes later, right? And it's got to be pretty to look at, and obviously needs to work offline when the wi-fi is down, right?
No, wrong. Everybody I know gets dreamy at first. It's your job to bring people down to earth. Simple text editing at best, and I do mean 'at best'. Basic UI, online only, unsexy solution. If you can't sell that, then you are either not solving the right problem, or it's just not that big of a problem to begin with.
Kubernetes, and Docker and CI? Cool tech, I suppose, but time wasters. Your release process should be scp-ing and extracting a zip file on the prod machine, or git checkout the files.
The one thing that went right was sticking with Couchbase imo. The world is filled with people who regret rewriting the persistence layer for an MVP under pressure. I am one of them. Several times over. Do not doubt the decision. It was the right choice.
Finally, schools and restaurants don't have money for software. I know folks who wrote school software. It was a travesty - the government gets involved at a certain point and wastes your time, the school budgets are razor thin and will not throw money at you. Restaurants are usually low tech as well. Most pay only for basic websites. Find markets with deeper pockets.