Integrating custom SLAM with ARSession

At 1000 realities we have been developing our custom SLAM algorithms for a while now, and would like to develop an UE4 SDK for one of them.
Are there any guidelines or documentation on how to integrate our custom SLAM with UE4’s ARSession object, similar to ARCore or ARkit?

Have you checked the plugins for GoogleARCore and ARKit ? Also maybe check the plugin for OpenXR.
Google also implements its own child class of ARSession, so you could implement your own too.
They implement a generic interface.