A gravel bike would be an on-trend trail shoe. In 2021 it will look very definitely like something from 2019.
It's 2023 and what we used to just call trail/walking shoes are now called 'gravel shoes'. They're basically running shoes with thicker tread on the soles. The guy that held the speed record for running around the world reckoned you could walk or run everywhere with just one pair of gravel shoes, even though they looked to me like running shoes.
I put my Doc Martens in the attic a year or two ago and have sort of forgotten about them.
I'm half-thinking of buying a replacement pair of lightweight walking shoes, the old fashioned kind made of leather, from when the UK still made shoes. You can't buy them new anymore, but there are some a bit like it which are really expensive now.