Build the damn app one time using SQLite on a single box. Then, figure out if the market even gives a shit about it. Building out a multi-cloud application architecture for your first prototype is a massive mistake. You don't need containerization tech if you can clone your application, hit F5 in visual studio, and the whole stack starts up automagically. You will probably find the performance of a single, powerful machine to be more than enough for your expected user base. SQLite can handle a fuckload of 'concurrent' writers if you know what you are doing.
There are now framework features available in some areas that help to obviate the need for containerization. If you are a .NET shop, look into self-contained deployments:
https://docs.microsoft.com/en-us/dotnet/core/deploying/#publ...
We have been using this deployment approach for ~3 years now and we have yet to have a single situation where a required dependency was missing or broken in production. And, we deploy to a very wide range of customer environments with all sorts of horrible IT practices applied to them.
Imagine being able to unzip a build of your software to a blank windows/linux server and expect that it work flawlessly 100% of the time, regardless of any prior/lack of configuration or other supporting dependencies on that machine.