[skissane]

HarmonyOS NEXT is based on an open source core, OpenHarmony [0], with proprietary additions.

So, not hugely dissimilar from iOS (lots of bits of which are open source, most significantly the core of its XNU kernel) and Android (considering that the proprietary Google Mobile Services is de facto a mandatory component)

[0] https://en.wikipedia.org/wiki/OpenHarmony

[lern_too_spel]

The Taco Bell kiosk and your exercise bike don't need the "mandatory" GMS.