On the Hiraracs web site forum which has some Pegasus testers they advise it will work with chess.com but for the moment only via the dedicated DGT app for IOS.
The DGT app on Android doesn't work with Chess.com. So if the iOS app is the same you cannot play on Chess.com with the Pegasus until March next year - the earliest.
I've already ordered the Pegasus and it is on its way but in the meantime I've been using the Square Off Pro.
It is a lovely board with excellent plastic pieces that feel great in your hand. It works with Chess.com and Lichess and if you take care when capturing pieces it works without problems.
I would highly recommend the Square Off Pro if you have the space. The Pegasus will be used on a desk.
By the sounds of it Pegasus still has issues with the software side of it. When we purchase stuff we kind of don't want the alpha version of the software. All that should be worked out before the release.
@karlth just ordered a couple of the Square Off Pros for my father and I for Christmas, looking forward to playing him on it :)
Chess.com doesn’t have the option for Apple products to connect with Pegasus as of now. They have planned iOS support for March 2022.
Best regards,
Sebastiaan Veldhuizen | DGT
Technical Support
Wow!! This has all been incredibly misleading on the advertising for the product with lots of broken promises.
I have no interest in Lichess on Android.
Also received a Pegasus and can not use it until the iOS app will be released. I only hope the app works, so I can at least use Lichess.
They announce a product with iOS and chess.com support, release and ship it. Now the customers sit with a product that is only partially providing the announced features and might not be able to use it. And after release they update their FAQ like this:
Pegasus works with Lichess, Chess24 (coming soon) and Chess.com. Lichess and Chess24 can be accessed via the DGT Chess app. Chess.com has its own app that works with Pegasus.
Note: Make sure you have the latest version of the chess.com app.
How should iOS users find out - before the purchase - that they cannot use it with chess.com? Still no references what is working, what is not working and when it will work. DGT should put out a clear statement explaining the situation and they might not lose the trust of even more customers.
The current behaviour makes me speechless. Let´s hope there will at least be some learnings.
I have owned 2 DGT autosensory boards. Back in the day of the Internet Chess Club I encountered frequent software issues resulting in the boards failing to properly register the movs of a game. I see that the company is offering in 2021 a new board with poor software support again.
The fact that DGT did not have a reliable IOS app at launch is consistent with the incompetence I experienced owning 2 expensive autosensory boards.
That makes it sounds like from the 16th December we can use with an IPhone and Pegasus but I am not convinced it’s gonna work. Maybe the iPhone app will be very limited and not gonna work over here on chess.com and they are playing with words???
If you purchased over 20 years 2 $1000 DGT autosensory boards and experienced the software issues I have you would not bet on a reliable IOS app.
Tomorrow I was going to go to my local shop where Pegasus is already in stock to buy it. After read all the issues that this board has, I have lost all the confidence in DGT. I have a Millennium King Performance that, although is not small or very portable, works perfecly well online with Chess.com, Lichess, Hiarcs, Chess for Android, White Pawn and other applications.
I will wait until the end of January and will buy the new Millennium eOne, inspire me much more confidence and can be connected to a computer to play against other engines.
I agree with your decision ivanacm7 to stay with Millennium. They offer a quality product which has reliable software. DGT has always been focused on making a product that is used by FIDE in official tournaments for broadcast. The home market has always been secondary to them, and truthfully they have never cared sufficiently to offer a great online playing experience.
Moundchargers I have not owned a Centaur nor know someone who has. The info I have read about the Centaur in the chess.com forums and elsewhere indicate there are questions concerning the quality of the pieces and board. Back in the 80s I owned the Mephisto dedicated computer, which today is the Millenium brand. My research indicates that Millenium offers a quality product that people report enjoy using.
The app is online now! 
https://apps.apple.com/de/app/dgt-chess/id1599508632
If you need help, please contact our Help and Support team.
That thing has some strange features. There is an LED next to the power button, which could have been used as a charging indicator, but isn't. You just have to guess when it's fully charged. When turned on, the LED blinks, but very slowly, so you can't tell at a glance if it's turned on or off. The power button itself sits on the edge, so that it can easily be pressed by accident even in a bag. A short press will turn it on, but you need a long press to turn it off, just to make sure that it stays turned on in it's bag, draining the battery.
Really, DGT?