Ask HN: Why are Amigas so inaccessible as a retrocomputing platform?

Since lockdown I've been playing around with a bunch of platforms that were around when I was young, but never really played with, I've made my way through the VIC, C64, Spectrum, and ended up around the Amiga where I got pretty stumped.

It appears all the software and firmware is super proprietary still, that seems a little bizarre, and especially weird there are no clean room implementations of things.

I'm mostly baffled because the platform looks great, it's almost the ideal thing I'd like to play around with, and there's basically a huge barrier to entry :(