How about some newspapers on the floor under the bike?
Assumes you have some newspapers lying around, and this is 2021.
The Gemeente send me one every so often, I don't understand anything written in it, and have yet to work out a way to not get it...
But in reality I have some big cardboard boxes that some ikea stuff came in, that I use to cover surfaces such as the floor and the desk when doing anything messy.
Also, I have one of those plastic matts that you put on carpet so that wheely chairs don't destroy the carpet, I do a lot of my work on this, and it's basically a wipe clean surface.
J