I don’t know whether you have done your painting or not but with your dark furniture and existing windows I would paint walls light warm grey and 150% strength same grey colour on the architrave .something different and grey , yellow and brown look good together.

Hi, we had the charcoal next gen decking installed 6 months ago for similar reasons - fully exposed deck, no time to maintain. Went with charcoal after much debate as we didn’t want it to look like fake wood but rather something different and modern. We’re happy with the outcome

The flooring is such a big component of a space you really need to consider it as part of the whole look you’re aiming for. I would say that generally for practically the carpet would be darker than the walls.

Lovely turquoise sofas, and your lounge has lots of natural light. What is the current wall colour? If you placed your sofas along both long walls, this would leave the window wall free for your view. Then you could have art on the walls behind sofas, or create a gallery wall of framed family photographs. A circular timber coffee table, or nest of tables, might work better in this scenario, with added benefit of no sharp corners for your little one.