On doing some research on randomness in Linux I found out about the
rng-tools package which includes rngd which can get
randomness from hardware random generators to linux /dev/random.
On the main homeserver greenblatt
there was no hardware randomness source available, I already use
randomsound to generate randomness from audio noise. I found out the
Raspberry Pi has a hardware randomness source so I installed rng-tools
and rngd was able to use it.
The impact on the measured available entropy is quite visible.