Managing products outside Magento

What I want to achieve is to update products with information from another app. So I wrote an app that communicates with Magento and the other app. Everything is fine, except I use Magento 2.2 and it doesn’t support bulk endpoints. As a result, using the API is slow. It takes about 4.5 seconds to update a product, but we may have to update up to 30k products in a night (worst case).

We have no plan to upgrade, so the current alternative is to send SQL requests directly to the database. However, it’s messy to deal with because of the EAV model. And I’d like to avoid to put the app somewhere in Magento just to have access to the framework. Of course the app should be able to work on its own.

Let me know if you know a lightweight tool that I can install to deal with Magento’s database or any other viable solution.