The objective of M2IF is to provide a fully functional replacement for the Magento 2 standard import functionality with a 100 % CSV file compatibility. In contrast to other approaches, the framework is not build as a Magento 2 extension, although it has no dependencies to other frameworks like Symfony, Laravel or others. Instead, it provides independent components, that can be tied together as needed, by adding them as composer dependency.
A simple command line implementation should give a brief overiew of how a simple import application could look like. For more information, have a look at the M2IF - Simple Console Tool repository
Import performance is one of the main topics, as in many, especially the bigger projects with more than 100.000 products, the necessary time to keep the catalog up to date, may always be a bottleneck or an issue.