I don't know if this suggestion would work for you but seeing as how difficult it seems to be (and I've read through the above) I thought I might as well throw it out.
If you can get your AOA into a ZAR account with little or no commission then you could open a Revolut account which will take ZAR and exchange to XBT at no commission. I suggest this because Revolut will accept ZAR (through a regular bank account) but not AOA. I am not familiar with South African retail banks, or apps, but maybe something like TransferWise or M-Pesa (well, not that one, but something like it) could help. Namibian banks take AOA and ZAR don't they?
My point is to piggy back the chain through little (preferably zero) commission steps. This isn't a solution, but I hope it gives you some ideas.