Are you sure? That’s just the Atmos demo Dolby have had on their website for a while. Spatial Audio isn’t the same as Atmos.
Since no one else has bothered to mention this clearly, Spatial Audio is not something unique to Apple.
Spatial Audio is a pretty generic term like "widescreen video" that encompasses a large array of implementations.
The Spatial Audio versions Apple iOS 14 and iPadOS 14 support are currently limited to Dolby Digital 5.1, Dolby Digital Plus (DD+) 7.1 and Dolby Atmos TrueHD. Note that the Apple presenter (Federighi?) during the WWDC keynote specifically mentioned these three audio format types.
Apple does not currently support DTS, DTS-HD MA, DTS:X spatial audio. DTS is a direct competitor with Dolby. There are other more obscure Spatial Audio formats as well. While their goal is the same (three dimensional audio) the technology used is proprietary.
If you buy a new A/V receiver today, you will likely get a unit that has support for multiple formats, at least some of the Dolby formats and some of the DTS formats. This was not always the case. And guess who is paying for it? You are. The licensing fees are buried in the price of the A/V receiver.
Content producers (like the film studio that releases a Blu-ray) will often prefer one format for the best lossless/high-quality audio track and offer their competitor's as a lossy alternative. Thus one can get high-resolution DTS-HD MA or Dolby Atmos but not both.
If you are like me and you have source material encoded in DTS that you want to hear in Spatial Audio on your APP, it needs to be transcoded into a Dolby format like AC-3 for it to be recognized as a valid Spatial Audio source playable by the TV iOS app and the AirPods Pro.
The same original DTS content works fine played back on my $60 Raspberry Pi 4 running Kodi/LibreELEC when the audio is passed through to my consumer-grade Sony A/V receiver. Kodi has wide support for a variety of codecs and file containers (like MKV) that Apple's own first-party apps don't natively support.
The limitation here is Apple's narrow choice of which spatial audio codecs the AirPods Pro currently support. Could Apple add DTS support in the future? Possibly. Would they need to pay DTS licensing fees? Undoubtedly.
Would Apple consumers be happy to see those extra codec licensing fees passed down to them? I don't know. However Steve Jobs famously called Blu-ray a "bag of hurt" and refused to pass on the substantial Blu-ray playback licensing fees to Apple customers.