Does the dock convert the signal from Switch to TV or is it basically a HDMI out? I don't see why they couldn't just have a HDMI port (with converter inside the handheld) that you can plug into the TV.
The dock is not just an HDMI put, as it changes the entire functionality of the Switch itself. Everything is in the Switch itself however, and the dock just uses low voltage signaling to trigger the "switch" from handheld performance to docked performance. This is why third party docks require you to use the same chip from an official dock, as a sinple HDMI out would just project handheld performance to the TV.
With that in mind, it should be nothing less than a firmware update and Nintendo to make a smaller dock sold separately to allow for portable play. However there is really no major demand for this unless someone buys the cheaper LITE, and decides later they are willing to buy a dock. Otherwise buying an actualy Switch, which is superior in EVERY WAY with the new revision wouod still be the best possible option.
In short, there almost zero reason that the Switch LITE should be dockable. It is just a smaller cheaper version for kids or those who will only play on the go and want to save 100 bucks.