Yarrow and weak cryptographic keys on macOS
A 160-bit seed is plenty for a cryptographically-secure PRNG. We are not going to be able to count to 2160 any time soon, so there is no need to worry that this is a "gaping hole". While in theory Linux's random driver may have a larger keyspace, it's not going to make a difference in real life. Fortuna does have advantages over Yarrow, but a larger key size is not what's important. What really matters is resistance to side-channel attacks and adequate entropy collection at boot time.

By default, Yarrow-160 actually uses 3DES in counter mode to generate the random output, which gives it approximately 112 bits of security. Fortuna uses any other block cipher in counter mode, but typically 128-bit AES. The Linux randomness driver uses ChaCha20. It starts out with 320 bits of secret material (a 256-bit key and a 64-bit nonce). Each reseed updates the 256-bit key. So yes, Linux has a larger keyspace. No, this doesn't matter in practice. Yarrow, Fortuna, and Linux's CRNG are all secure.