the reverse was actually possible: there were PC compatible expansion cards for the amiga [1]. The issue is that they were very expensive and 8088 only.
Yes, those PC Card addons for Mac/Amiga/etc are endlessly fascinating to me. But with the benefit of hindsight, the crucial factor wasn't just being able to run DOS applications on your fancy propriety computer, it was riding the PC Compatible rocketship as it blasted off. Creative Labs and 3Com and Tseng and many others showed that there was more value in manufacturing a popular expansion in the massive PC world than in owning your own closed platform bow-to-stern.
[1] for example: https://en.wikipedia.org/wiki/Amiga_Sidecar although "card" is stretching it :)