Why do I only see the PC version in the downloads ?

Shouldnt there be a Mac version now, too ?

It is available on Mac but not through GOG. Have to go through Steam or go through Apple (I think). The NoMansSky.com website by Hello Games has a link directing you to Steam for the Mac version.

Ah, OK.

I own no Mac ... though I'm thinking of getting one. As a basis for a Linux installation.

It's Steam only. They promised to bring it to the Mac App Store, but that never happened and they never explained why.
It never came to any other platform either, including GOG. Only Steam got it.

Mac was their most recent plattform to release NMS on, I think it was only last year ?

So maybe they'll offer it on GoG, soon, too ?