Its weird, I remember recently seeing a post from a FlightAware Staff member. He was responding to a similar question and said there had been delays due to the Chip shortages but they hoped to have them out by November. He said they performed very well. He seemed very excited.
** Edit, I found the post that talked about this. Ive pasted it below :
"esmathewsFlightAware Staff
Yes, FlightAware is working on a new SDR we’re referring to as the Pro Stick X. I’ve mentioned it in passing here and at my presentation at Oshkosh. Appreciate you noticing!
We are several rounds of prototyping in now and the performance will well exceed that of either of our current SDR products.
The global component shortage has been a challenge for this and two other new product lines we’ll be debuting, but we anticipate to be selling all three no later than November of this year."