I see in How do I import an assessment from a QTI package in New Quizzes? that New Quizzes only supports imports from QTI 1.2 and 2.x.
I can fully understand why Legacy Quizzes can't import QTI 2.x -- certain question types don't exist in Legacy Quizzes. However, why can't this earlier QTI definition, which does match a subset of question types in New Quizzes, not be supported? That is, why draw the line for backwards compatibility at QTI 1.2?
My primary difficulty? The current version (4.0.8.06) of Respondus QTI publishing provides two options for export:
The Canvas Import process will upload a QTI.zip file (though the file filter shows .zip, .imscc, .mbz, .xml), and when selecting the exported QTI 1.2 xml file for either Legacy or New Quiz, that import results in a failure.
If you choose the zip file version and indicate "New Quizzes" during the import, a New Quiz is created with no content. This is in line with the supported QTI version, though I would suggest that NO quiz be created and that the import end with an error indicating the version discrepency.
I will follow-up with Respondus to update their capabilities. (Yes, I also know about the Respondus ability to publish directly to Canvas -- but that is only for Legacy quizzes.)
As of now, you are correct in that New Quizzes doesn't support other QTI versions. As for third-party tools such as Respondus, Canvas recently integrated with their LockDown Browser, but ultimately I think you'll want to put your vote into https://community.canvaslms.com/ideas/10545-new-quizzes-should-support-current-third-party-tool-func.... Contacting Respondus is also a good idea about seeing their plans to integrate; right now integrating with third-party vendors is still based on custom code, and Respondus may be interested in furthering their product within Canvas.