Other filters will be same part but different temperature range; same MCU but different footprint (which would require a board re-spin but not normally the end of the world).
You'll also get SKUs where different peripherals and flash is available which is generally the same die, but not everything worked when tested at the fab so it will get binned appropriately.
There's other filters but I guess I am saying the total number of SKUs of die that are getting made is not anywhere near 3000.
You are right with the 730 day lead time. Actually anything beyond a year you can interpret that way.
Even when there is stock, the parts will be on allocation anyway. Normally the biggest existing customers get first dibs and everyone outside of that circle is given an absurd lead time. Sometimes you can push your way in if your order is big enough.
I feel for the PlayDate team. It's not a fun time when this happens. Even my usual rule of "make sure there are at least two alternatives if possible" is failing in this shortage.
We've even resorted to ordering dev kits and scavenging parts from there which is good fun :)