Rumor: Nintendo Switch 2 Console 'Leak' Hints at New Feature (Scroll Wheel Triggers and Traditional Console instead of handheld)
https://gamerant.com/nintendo-switch-2-controller-scroll-wheels-leak-rumor/
The weird thing is that it seems late for Nintendo to still be working on R&D for the Switch 2. This is probably less than a year from announcement. At this point, I would expect them to be hammering out agreements with suppliers, so the hardware should be more-or-less done.
Then again, I have no idea what the timeline is like for console development.
It's not weird at all. They'll be tweaking things they don't have signed contracts for right up until reveal, and they won't reveal until the tweaking is done.
What's being sent out to developers are formless computer boxes that either house the performance hardware that will be used, or have very similar specs to what's expected to be in the final product, plus the operating system, SDK, and accompanying libraries.
At my last place of work, we had some Wii devkits in storage. They looked like old stereo equipment, and told you literally nothing about what the system would look like out of the box.
The thing with R&D for a company like Nintendo is that they're never finished. If they've really finalized the Switch 2 as you've said then R&D will have immediately started working on the next console, or at worst post-launch accessories.