I do something similar but this only protects secrets at rest. If you app has an exploit an attack could just export all your secrets to a file.

I prototyped a solution where I use an external debugger to monitor my app, when the app needs a secret it generates a breakpoint and the debugger catches it and then inspects the call stack of the function requesting the secret and then copies it into the process memory (intended to be erased immediately after use). Not 100% security but a big improvement and a bit more flexible and auditable compared to a proxy