I've seen water hammer suppressors that fit between the appliance hose & the connector:
but I don't have room for one of those under the kitchen sink, especially since I think it has to be installed pointing up.
There's also the freestanding kind:
which says "single-appliance", but I would have room to fit that to the cold water supply running through the crawl space under the dining room to the kitchen, & only one appliance is causing hammer. That one says 1/2" BSP, so I guess the installation method is to cut a gap of the right size into the water pipe & fit a tee with a 1/2" BSP pointing up --- is that right?
I'm also thinking of trying some more "improvised" measures first, such as wrapping the pipe in rubber (old bike inner tube) & clamping around that to a joist --- is that realistically likely to make a difference? (The pipes below floor level are already covered with insulation & expanding foam.)