Fun fact, making extensions for this requires you to learn a new language called X++ that is based on .net framework 4.7. Development is done only on azure-hosted VMs that contain the application code and sql server and web host and visual studio with the special X++ build tools, all on one host that runs like shit at your expense.

I have been developing plugins for dynamics 365 crm for the last few years and have never heard of x++. Plugins for the crm are developed in c#/.NET 4.6.2.

The only x++ reference I could find in the Microsoft documentation with a quick search was referencing the finance and operations apps. So there seems to be some variance in the products.