As far as I know, that's the case as long as you're using GnuPG 2.1+
That's awesome. I didn't know these things. I never used this software.
Unfortunately, at this time, I don't have an Android smartphone or an Android Emulator to try the PGP application.
However, after I tried to look at the details of the Public Key that you generated using the OpenKeychain application, I confirmed that it was not a 4096-bit RSA but a 3072-bit RSA.
My bad. Yes, it is a 3072-bit RSA. I do not understand the difference between the 4096-bit RSA and 3072-bit RSA. But when I try to import another key generated by OpenKeyChain, it shows the key is 3072-bit RSA. This app doesn't give me a choice to pick 3072-bit RSA or 4096-bit RSA. So, 3072-bit RSA is generated by default from Openkeychain.
By the way, it seems that you forgot to delete one empty character before writing -----BEGIN PGP PUBLIC KEY BLOCK----- in the public key code above.
Thanks for pointing this out. I fixed it.