Covering and cladding formwork stone wall - what are the possibilities?

But since I have to paint 60m of wooden fence every 2 years, I am foregoing wood here.

Then take larch. You don't have to treat it. Over the years, the color changes from a light, almost orange tone to a silvery gray color. The weathering does not affect the wood's substance and, in my opinion, looks great. We have the entire house like that.

Maybe I am also mixing the different walls. For example, plastering at the stairs and maybe wood on the straight sections

It's me again, so I'll probably just paint the walls to keep the effort low. After that, more planting will be done. Can anyone recommend suitable colors?

I'm currently in the north of Portugal. The very humid winters put a lot of pressure on buildings through plants and moss. Here there are tiled walls and houses that don't mind all that. That made me think of your wall.