That's another thing I speculated about previously, but have changed my mind on. There's no point to such hardware anymore. In the past, devkits were the only way to run, say, a Nintendo DS game during development. Now that the NintendoSDK exists and supports running NX games/libraries on Windows, that's good enough for all the early development that an ad-hoc or Orin devkit would enable. A final devkit is important because you need to run in the actual environment and on the actual specs of the final hardware, but an ad-hoc devkit doesn't give you either of those. Orin running L4T is useful for Nvidia to develop drivers, but it doesn't offer significant advantages to game developers, and third parties using either that or an even earlier ad-hoc box just adds extra expense and complexity.
As I said before, the NintendoSDK doesn't run on Linux, so it's unclear how a devkit like that could have been made to work even if it was a good idea. I think it's entirely believable that only SDKs had been distributed prior to Drake being sampled. As the latter seems to have happened sometime last year, that's enough time for third parties to move development to real hardware ahead of a possible 2023 release. For comparison, Nintendo's original plan for the Switch was to distribute devkits in November 2015 and launch the console pretty much one year later. Then the devkits were pushed back a bit, and due to the release date being delayed to March 2017, third parties ultimately had a year and a couple months' time with devkits before launch. Nintendo doesn't have to follow that same timeline again, but it gives you an idea of the kind of schedule that's possible.
Whether SDKs really were distributed all the way back in late 2020 is still questionable to me. If there was indeed some kind of delay, or "evolution" of hardware in how it was being produced or positioned, or whatever, that could explain why the process started that early. Or it could just be that Nintendo was fine with a longer SDK-only period this time, with the Windows SDK being mature and much easier for Nvidia to start adding new features to without waiting for HOS or hardware.