IMO Amazon is the obvious choice for TEE because they make billions selling isolated compute
If you built a product on Intel or AMD and need to pivot do take a look at AWS Nitro Enclaves
I built up a small stack for Nitro: https://lock.host/ has all the links
MIT everything, dev-first focus
AWS will tell you to use AWS KMS to manage enclave keys
AWS KMS is ok if you are ok with AWS root account being able to get to keys
If you want to lock your TEE keys so even root cannot access I have something i the works for this
Write to: hello@lock.host if you want to discuss