Trusted execution environment (TEE) on IOS and Android

In the field of financial technology, there are many discussions about the use of trusted execution environment (TEE). I know that on IOS and Android, some key store APIs can be used to generate keys and use them for signature / decryption. However, the code written by myself is running as an ordinary application

My question is, is this the only use tee can use? Or can ordinary application developers (i.e. not developers from mobile phone manufacturers) write the code in the application and run the application in tee? I haven't been able to find Google or apple documentation describing how to do this. Is there a special API?

resolvent:

Different devices have different tee. Op-tee, trust tee, QSEE, Tlk, kinibi (formerly T-base, formerly mobicore), etc

As far as I know, only kinibi (since mobicore) allows application developers to develop / deploy "trusted applications" with ordinary applications (without OEM signature)

At least using the global platform standard API, your TA may be source compatible between tee