Neat! This reminds me of urbit sigils[1]. The problem with urbit sigils is that they only support 32 bits of entropy because that's the size of urbit's owned real estate space. These hash avatars support 8 times the entropy and also directly map to a 256 bit public key although one may want to be slightly careful mixing the use cases without some other visual queue (this is a sha256 vs this is a pubkey).

[1]: https://urbit.org/blog/creating-sigils/