You just need alsa-sndio when you want to run alsa through sndiod, but in general I recommend to leave that package outside. The point being is that you have two sound-systems throughout the Linux-kernel using alsa and sndiod is running besides also. Removing alsa-sndio gives you the opportunity to run applications using ALSA with ALSA and the rest without issues with sndio.
But you need first to verify that alsasound is running as daemon. Additional to use a mixer like volumeicon for ALSA. Making your sound working first with ALSA and when this works you can verify also sndio. But to underline: As sndio is most a BSD-descendant software Linux is not supporting all parts very well with any graphical interface or better said: It could and would, if people would be interested.
Human being in favor with clear principles and so also for freedom in soft- and hardware!
Certainly anyone who has the power to make you believe absurdities has the power to make you commit injustices: For a life of every being full with peace and kindness, including diversity and freedom. Capitalism is destroying our minds, the planet itself and the universe in the end!