The non-Tesla Supercharger Pilot recently expanded to all stations in the Netherlands and is available at some stations in Norway and France.
We already know that in some cases there are issues with geometrical compatibility, due to short charging cables and various charging inlet locations.
However, this is not the only thing that was noticed. According to Bjørn Nyland's recent video, there is also a problem that the plug is not securely locked while charging a non-Tesla EV at a Supercharger.