Plastering work Q2 - Painting work afterwards?

You do have a basic idea that you don't like or need smooth walls, which is already helpful for making a good decision. Here you have now read the variants, but ultimately everything is possible and you can make something out of everything that you like. Back then, many years ago, we applied white Streichptz in a crosshatch pattern and afterwards got a great result with a glaze from Caparol; at the time, earthy tones were popular, which I still like today; it then looked rather marbled and really good. Later on, we also worked with it in a single color, so I never had to sand it off. It simply depends on your desired goal and that you say you want to do it that way because there are no children and you’re in the mood for it — that's great, and then I would also look for exactly something like that, which I would also do myself (willingly!!!) work-wise. I believe you already know what you want and now just need to decide on or try the suitable product, color, technique. Changes often come during execution anyway, at least that's how it is for us :D

I’m not a painter, so I can share my opinion with you.
I would tint the paintable plaster with the matching tinting color. Of course, you can mix everything, but ultimately you would be mixing Knauf paint (with sand grains inside it becomes paintable plaster) with Alpina paint, which makes little sense to me. You can have any desired shade mixed by the painter (or yourself) to match your paintable plaster. Since you probably need to paint twice anyway, it would be worth considering doing the first coat with white paintable plaster and the second with paint. For the second paint, I would perhaps pay attention to whether it is scrub-resistant depending on the amount of wear.
I once had a terrifying experience testing mixing when we wanted to beautify our bedroom with a textured plaster at that time. We even bought a Venetian trowel for it and experimented, everything according to the painter’s instructions. As a primer, we were told we could use "normal" white paint, and we cleverly used Alpina white back then. After that, we painstakingly applied the plaster thickly, and the next day the paint was supposed to go on..........
We were shocked because the entire plaster in the room had cracked and looked like a dried-up waterhole in the desert. We then had to remove the expensive plaster layer by layer with a spatula from the wall; more or less it fell off by itself because it had no bond with the substrate. We were later told that the paint (used by us as a primer) had virtually drawn the water out of the plaster. What a drama that is amusing to look back on today.
But that says nothing about Alpina, because they recently received top test results for some products; it just didn’t work together at that time.
I would take 1. white paintable plaster and then paint; otherwise, you end up with several paint cans lying around.

Alpina-white (ORIGINAL - very important,

Always just the ones with the cat! (Filler words into the toilet also make the cat happy)