Alien Dalvik is a great idea and theoretically works well, but it's proprietary software and its developers don't seem to have any interest in anyone actually using it.
There doesn't seem to be any free software effort in prong
porting ART to a real linux system (which shouldn't be hard at all), which could've happened for years and I'm not sure (though shyly hopeful) the Librem 5 will change anything about that (so the only realistic option would be full emulation, which would require a good bit of power).
Edit: Just realized that you could theoretically run Android apps via Chrome. But shit, that'll be slow.