Will someone eventually turn the Echo Show 11 into an Android tablet with software todo Home Assistant dashboards on it ?
Maybe, but I wouldn’t buy one planning on that being possible.
AFAIK, the first full exploit to get Android on the Echo Show 8 (Gen 1) was just released a few weeks ago… and that thing has been out for nearly 6 years. Also, with Amazon transitioning to a more proprietary OS, it seems likely that it might take even longer for exploits to be found for newer devices.
If nabu casa pays amazon you might see home assistant advertisment on it… but probably not much more 
Side note, Echo show 5 can be internet into something useful finally 