I’m certain there would be a new generation of startups especially focused on selling digital goods.

Further, you need to look at incentives. Apple would almost certainly respond by lowering their fees as a move to stay competitive. That extra cash trickling downstream would enrich many more people, who then would go on to create new things.

Not sure you have an argument that it would already have happened if it was so much better.

If the vast majority of devices already have this capability, what difference is it really going to make forcing it on the remaining 20%? Why hasn't Apple already been forced to lower their fees if they are the underdog in terms of market share? For that matter, why hasn't Google been forced to, given how easy it is to sideload?

Apple has dominance in many markets, like the US. In fact you could say the reason Android has such global market-share is because they commoditized their OS, ie, allowing for competition to drive down prices. So you're claiming the same forces wouldn't affect software? Android apps are generally cheaper, as well, though it's hard to pin why. The general principle of competition = lower prices applies here.

I'd rather debate on what's right for consumers not whether some technical definition of a monopoly applies or anything like that. But to be honest there's not much more to be said - if you are against the legislation, then fine, it's a perfectly valid opinion. I think legislating allowing more freedom on personal general computing devices would be a good thing with many benefits to society as I've enumerated already.

This seems on the surface to be the libertarian position, but imho it's subtly authoritarian - you weren't able to convince most people to use the freely available unlocked hardware you're advocating for, so instead you'd like to use the full force of the law to make all product designers create what you want them to create. If the benefits of unlocked hardware were so evident, surely the consumers would already be reaping the rewards on the unlocked hardware they can buy right now?

Libertarian philosophy is maybe the least compelling of them all in my opinion.

Safety and accessibility are human needs, and regulating markets to address those needs is a completely reasonable requirement.

Forcing product designers by legislative fiat to add a cool feature you want, on the other hand, is pretty authoritarian. Nothing is stopping you from buying a general purpose computing device right now, or building one and selling it.

You’d have been pro Bell I guess back in the day. “What’s stopping you from building a competing telephone service?” Oh only not having capital > all VC investments made in any given year.

Correct - and Google's very popular, but not dominant OS will already let you sideload whatever code you like, which is a big part of why you'd have a hard time competing. I'm sorry, running arbitrary code on your daily driver phone is just not the game-changing feature you're making it out to be.