Have you wrote to Apple (via Feedback page) regarding this yet? This seems like a huge oversight. It would be incredible to take advantage of all speakers across 2 displays - it is that type of synergy that would encourage folks to get 2 ASD instead of say 1 ASD + 1 LG Ultrafine, etc.
I believe this feature is already available in MacOS. You can combine multiple output device into an 'aggregate device' in Audio MIDI Setup. Then set this aggregate device as your default audio output. You'll get sound from both monitors.
I wonder how many people who have an ASD actually stick to native scaling? I certainly wouldn't be happy with only 1440p equivalent space on such an expensive monitor.
I run my 4K 24" at 2240 x 1260, which is not native, and everything is pin sharp at 50-60cm viewing distance.
I won't doubt about the sharpness. Not everyone still have a pair of young eyes, especially for a 24-inch (!)
Of course the more likely reason you haven‘t heard of it is because it’s not a thing but, please, continue reasoning backwards from your desired conclusion. I’ve always thought contortionists were fascinating.
You may also continue to deny. The army of Apple Privates fascinates me as much as the opposite for you I guess.
If the product was just that little bit more affordable, or upgradeable over time, for example buy the cheapest ipad pro, then in a year save up and upgrade.. I would have done this for my 2013 macbook pro laptop, and my 2013 ipad mini 2..I am willing to invest in "Apple Tax" think of it like buying a new car, you know going in, that you will need new tyres, new exhaust, annual service, new brakes, think of this as vital upgrades...So you budget for it...
Buy stuff that suit your need. Whether it's by Apple or not is secondary consideration.
I won't realise 4K LG works out so well until I gave it a try. Before my decision, there were mountains of misinformation about how bad 4K monitors work in MacOS, and sound the alarm of the mandatory of 5K. Heck. At a normal viewing distance, a plain-old 1440p 27-inch iMac screen appears about the same to a 4k 27-inch in 'look like 1440p' mode.
I envy those eagle eyes who claim to tell apart a 5K from a 4k at 'look like 1440p' mode from a normal viewing distance and in a double blinded test.