As has been mentioned in a few forum discussions here, exporting the aligned cameras as XML results in strange transformations: Metashape uses it's local coordinate system with no obvious correlation/transformation matrix to the "real" coordniates. Only option is exporting as "omega phi kappa", but this lacks other information, such as camera intrinsics.
Both instant NGP and Nerfstudio have scripts for converting Metashape-camera.xml into their own format (transforms.json). This resulting file however inherits the "arbitary" transformations of the original Metashape xml
Sure, Nerfs are still in an expiremental phase, but IMHO the future potential is obvious! Thus, the combination of the solid alignment from Metashape (with all the options in this phase, i.e. individual pre-calibration, masks, and and and) make it an ideal fit for Nerfs.
So PLEASE, adjust the XML export, so it obviously reflects the user-defined local coordinats! That would be such an opportunity!