Comment by bonzini
The Amiga was loudly marketed as having a 32-bit CPU though (the Atari ST a lot less so, for whatever reason).
Having a 16-bit ALU in theory would make the 9900 a 16-bit processor as much as the 8086. The TI-99/4A is definitely weird (and slow!!) but it does fit the definition of a 16-bit system.
The ST very subtly so, even :)
> "ST" officially stands for "Sixteen/Thirty-two", referring to the Motorola 68000's 16-bit external bus and 32-bit internals.
via https://en.wikipedia.org/wiki/Atari_ST