What does it have to do with forcing Apple to allow installing iOS software outside of their approved appstore? Manually installed FF from hypothetical non-Apple store will somehow magically pass remote attestation on iOS or what?

It has everything to do with it. Computing freedom is paramount. We should be able to install whatever software we like on our machines. Therefore it follows that corporations shouldn't be able to discriminate against us for doing so.

Things like remote attestation should be illegal.

So it is not related at all either to the article or my previous comment? Okay...

Your comment was essentially "but you can exercise your freedom if you want to". I said they will discriminate against you for exercising your freedom, robbing you of choice. "Whatever software you want", provided they belong in the set of software approved by Google or Apple.

If you still don't see how it's related, I don't know what else to say.

I'm pretty sure I have multiple programs installed on my phone that weren't approved by either Google or Apple.

Then for your sake I hope they don't find out about those apps. It is their device, after all. They don't like it when you do things they didn't approve of. Their methods grow ever more sophisticated. Hardware cryptography is only the latest innovation.