Vaporware is cheap.
Working out the details and delivering a properly working product, like the commercial says "Priceless"!
Not to knock anyone at Uniden, they made the same age old mistake that many vendors and others have made time and time again, rely on a 3rd party to provide an assembly and did not thoroughly vet and test the product. Either assumed it worked correctly and/or took the vendors word that it worked correctly. WiFi and networking is a complicated technology.
A scanner and networking are 2 very different disciplines and rarely, if ever, do the 2 disciplines cross, much less merge into a single product. There are FEW people that have the experience to glue these together.
This chore is not a simple and easy thing to do, otherwise it would have been done a long time ago.
I wish every bit of success to Uniden and hope they can get everything sorted in a timely fashion, but I would not be expecting the WiFi and Siren App to be available in the near term.
Overall the 536HP does have a lot of good features and performance, so assuming you do not need or want a handheld scanner, I would still recommend a 536HP regardless of the WiFi and Siren App.
I mentioned this before, Uniden should offer a hard wired 100BT USB interface, this would GREAT simply things and would make the 536HP a far more flexible platform.
AOR AR5000+3 & SDU, AR8000, Icom R71A, R7100, PRO2004, PRO2006, PRO43, PRO96, PRO2096, BC785D, HP1E, 396XT, 996XT, 436HP, 536HP. Probably missed some gear. Man, I gotta get rid of some of this stuff!