While there's no official support for aga it is possible to use aga without any extensions. You are however still restricted by amos/amos pro itself a little. By this I mean no 128 or 256 color modes, 64 colors is only available in ehb, no aga sprite modes, no 1280xX screenmodes and so on. You can however use double bandwidth mode, 32, 64 and 4096 colors in 640xX screens and a few other AGA-isms.
To do so you simply need to set up a simple copper list that will make amos use aga equivalents (in ocs/ecs color precision though) to what amos/amos pro offers by default.
There's some easy, ready to use examples on aminet by Chris Hodges (he of amcaf and poseidon usb stack fame) that show a person how.
This is probably the closest thing to useful use of aga for amos available. Anything else is such a chore, and limited to use to a point you may as well learn Blitz instead
