Publish the protocol docs. That's literally all that's required from them. Actually they don't even need to - they can just promise not to sue anyone who reverse-engineers it and publishes a commercial client.
That's how adversarial interoperability worked for decades (and gave free software the ability to interoperate with proprietary formats, see LibreOffice for example) before abusing the DMCA and/or threatening legal action to take down compatible implementations became common practice. I do not recall of any security breaches as a result of this.
Apple are however not going to do that, because doing so would overnight destroy their moat around Universal Clipboard and all their existing interoperability features. So instead they make up some bullshit that non-technical governments and courts will take years to disprove, buying them more time to operate anti-competitively.
It is however sad to see a member of a technical forum gobble up said bullshit.
Can you articulate where in the DMA where it says that all Apple has to do "is promise not to sue anyone" to be in compliance. Or where it talks about protocol publication.
The DMA is about preventing gatekeepers from using arbitrary restrictions to prevent competition. It does not try to predict and anticipate every possible example nor solution.
The existence of competitor would by itself be enough proof to the fact that Apple is not restricting competition. But for such a competitor to exist, they would require enough assurance that the business will be viable and they won't get sued out of existence.
Apple either publishing the protocol or at the very least publishing an official licensing agreement allowing anyone to reverse-engineer and reimplement said protocol would achieve this.
Evidence could be that Microsoft isn't in trouble for shipping Windows with RDP servers/clients in Europe, which is equivalent to this iPhone mirroring feature.
Why is Microsoft able to do it just fine (without running afoul of the DMA) while Apple supposedly can't, despite MS having an ever larger marketshare of its field than Apple and this would warrant even more scrutiny?
The multitude of third-party RDP clients (and nobody being threatened with legal action for implementing one) out there may be at least part of the answer.
I know that Apple wants their cake and eat it too, looking for ways to wiggle out of this while still dodging their responsibilities. This is why they need years and a small army of lawyers.
