> - Can't run my own version of AMO

You can, AMO is open source: https://github.com/mozilla/olympia

Run your own instance and make your own builds of Firefox that point to it and you're good.

>make your own builds of Firefox

Yeah, let me just get all of the potential users of my AMO alternative to compile a custom version of Firefox for it

If you want to run a custom AMO I'm assuming you're in a corporate environment or something like that where you can control what browser gets installed on people's machines.

https://addons.mozilla.org is an integral part of Firefox, if you set it up with an alternative you're effectively making your own fork.

It's not an integral part of Firefox, though. You can install add-ons without it by just clicking a link on any page that leads to an XPI, same as how AMO behaves.

And no, I'm not in a corporate environment. I'm talking about decentralization.