AWS Bedrock seems to say the inference code is only scanned for CASM and no one trains on your data.
I felt like "Confidential Compute" tech could solve this issue once and for all but I'm not so sure after seeing some of the attacks people can do with physical access.
Another option of course is to not use cloud at all and have your own rack in a locked room with a good security system and/or armed US person guards.