Good call out! I'm keeping an eye on Fleet. About a week ago they opened a private beta of the plugin SDK, I registered but got no news yet.
It's a bit sad that it can't use IJ plugins, but that's expected and probably for the best! It means they're focusing on the future. đ
I'm hoping the API will be top notch (for instance you can feel the "Javaness" of the IJ plugin SDK in lots of places).
We can still hope we'll be able to reuse some code, since at the very least it will be Kotlin, plus if I understand correctly, Fleet re-uses a lot of IJ under the hood anyway. (Also, a bunch of code of our plugin is 'glue' with the Apollo Kotlin code, that's not too specific to IJ, so at least that should be reusable).
We'll see how the ecosystem evolves - but for sure if lots of people use Fleet, we'll certainly want to offer a plugin!