APPLE II SOUND CAPABILITIES (VST PLUG-IN)

So, I would like to know this and I can't find an answer anywhere (or I'm dumb). I need to make some tracks imitating Ol' Apple's limitations.
Do you know what they were? On Wiki i found something about music cards and how they did enhanced it. That is not what interests me. I want to know about the built-in chip (it probably depends on model)

My questions are:
How many channels did it disposed with?
Do you know any VST plug in or sample pack?

There are some examples of great Apple 2 soundtracks:

Karateka has the feel, I'm likely to aim for the most.


Ultima IV has very clean sound.


There are some brilliant bits in Space Quest (1:38)

This may seem to be chaotic or that i don't know what i want. The truth is, that I don't know too much about microcomputers and the oldest computer I have is a win95 laptop. I'm planning on buying one (probly something slightly awkward like Amstrad CPC). So, any advice is welcomed.

Edit: I found this comment on youtube, which is pretty interesting.

author=Carlos Duarte do Nascimento
wonder how many simultaneous notes this player achieved. I remember having a hard time cranking 6502 code capable of holding two simultaneous notes (you had to properly time "clicks" on the buzzer by writing/reading to an I/O location, $C020 or $C030, IIRC). It was hard, and this player had a good result. Ever used Musicomp for Apple II?