These are my thoughts on the MOMS architecture:
Monolith with Opensource Microservices.
Basically, you write your app as a monolith because its quick and easy.
And when you have a subsystem of sufficient complexity and independent enough (doesn’t require being deeply enmeshed in your app), you split it out to a microservice that you opensource.
By opensourcing it, it makes you think of how other people might use it, so you make the APIs a bit more generic, you document it better with a readme, and you standardise the deployment so it’s easy for you to deploy.