No, all we know is that the people buying the playdate think they don't substitute. Whether these people end up being correct is completely speculative at this point. I'd like to hear an analysis why the same experience couldn't be had elsewhere, preferably by a seasoned game designer.
We know for certain that the games are exclusive to the play date and were written for the platform. Therefore we know that the same experience cannot be had elsewhere.
Even if the titles weren’t contractually exclusive, no other handheld device has the same combination of inputs, notably the crank, so ports of the games would not play the same.
Even if neither of these were true (which they are) we know the games are currently exclusive and have not been ported. Temporary exclusivity is a standard way to create non-substitution in entertainment businesses.
(I was a developer at a successful games company for 4 years. Not that an appeal to authority has any relevance. The facts are public.)
The crank isn't special. They're making it out to be, but it isn't. Any device with an analog stick can achieve the same. In 1996 Super Mario 64 on the then-new Nintendo 64 had players spinning the analog stick in rotary motion to spin Bowser by the tail. The Steam controller (and the new Deck) have track pads that can emulate rotation. The Nintendo DS had a touch screen you could draw circles on. Every computer mouse since like 30 years ago has had a scroll wheel. Heck in my local game museum there's an ancient Pong game console and the controllers literally have only knobs to twist to move the paddles. Stop pretending like this is some novel innovation.
Playdate is a boutique product selling a few tens of thousands of units. In fact the games are unique.
The fact that there are other cheaper games which sell in much larger volumes is irrelevant to whether there is a market for a boutique gaming experience.
We know they don’t substitute because if they did, people wouldn’t buy the playdate.