All retrofit autopilots are by a validated FAA STC. S-TEC (now Cobham) have STCs for most aircraft and there are many validations from UK CAA OR German LBA as well as the later ones from EASA. If you want to install a system that has an FAA STC but isn't validated in Erope, S-Tec charge about $1200 to deal with the paperwork, which can take 6 months to get through EASA.