x86 emulator
Unicorn based emulator as a debug adapter is apparently the best option, but the GPL license makes it hard to use in binja. Might need to distribute it separately from binja
An alternative is the Triton framework (https://github.com/jonathansalwan/Triton), which is licensed as Apache 2
Triton itself is not primarily an emulator, but it can be leveraged to do so with some proper engineering
Bochs can be used as well, though that means we have to write some code to boot the machine from scratch, switch the CPU to protected mode, and load the code into the correct place. Which is FINE since we only need to write it once
See also https://github.com/Vector35/debugger/issues/521