I could do a redirect (it would require a small firmware update)
But that would still expose your authentication credentials to the backend, so a malicious backend could MITM you.
Reducing the polling is definitely an option, I want to make that configurable very soon.
Btw, the cached data in the backend is encrypted with a token that is only transmitted from the device to the backend during the API request of the device. It's not end-to-end, but it's a step.