I have. Usually have odd sized fitting and require some adapters.I've used these guys a few time for parts on my Aqualisa shower. You can buy cheaper brands but if you go with one of the big players you'll be able to get the parts if needed in a few years time.
https://www.showerspares.com/all_new_showers/all_bar_mixer_showers/
For example my Aqualisa is probably 20+ years old and they have always had the parts in stock.
I'd never heard of @CompoSimmonite Hansgrohe but they list internal parts back to the 90s for some of them