If we are scratching the I2P as mechanism then what about generating a special purpose onion key that you’d run from any personal device at your disposal to communicate with users via Whonix News? Of course Whonixcheck would be modified beforehand to look for or ping this dormant onion.
Its slightly different from the Tahoe idea in that it is not asynchronous, but both would depend on you having a trusted key as a URI for Whonixcheck to look for.
As for image distribution it would happen via I2PSnark. Hosting apt packages and even git could only be done with Tahoe though.