I could imagine that it would not be possible to use floor tile
adhesive on wall tiles, as the tiles need to be held in place while the
adhesive sets, but wondered if the opposite were true.

No. A quick read of the recent thread "tiling on wooden floors" will
indicate the need for a good floor tiling adhesive.

I would recommend Ardex Flex 7001 Timber System for a wooden floor, and
Ardex Flex 6001 for concrete.

Christian.