I think if the paint of the wall are the same with the cabinet it will look better,

imho the ceiling cladding seem in better condition than the floor only from the pic, but I agree it should go,

the problem is the floor cladding color not match well with countertops and furniture like tables and door so it feels like not unified,

you already have dark wood color floor, bright wood color countertops, and white cabinets, so the different paint wall make it full, we usually keep 3 color as theme for a room,

thats why when buying furniture we usually bring picture of our floor or any existing wood furniture unless its the house concept to not symetry and each has unique

Making the ceiling white and adding plenty of downlights should make the whole space feel bigger and allow for some darker colours on the walls. It's definitely worth also thinking about your countertops, and maybe switching to a brighter option.

Here's one of our kitchen renovations where we used dark green paint with dark wood and brick, but kept the space light with white counters, backsplash, ceiling and floor. Plus a great pendant lighting moment!

I would also paint the surround of the exterior doors white and maybe consider changing the obscure glass for plain glass unless privacy is essential. I think it will feel more spacious if you can actually see outside, your eye will travel further than the window.

With lighting, especially in a kitchen, the key is to think about where you want the light to shine, not how uniform or otherwise it will look when you look up (cos you generally won’t look up!) think about where you need light - usually just out from any wall units shining onto your worktops in a position your own head won’t cast a shadow.

Definitely replacing the ceiling with plasterboard and painted - coving won’t work all the way around from what I can see in the photos (door frame hits ceiling? So no space for coving there which would look weird?) you’d have to lower the door frame & door which is possible. Or just don’t have coving.
I don’t think you should go a dark colour, if anything white! It’s a gallery kitchen. What this kitchen needs is some plants I think. Maybe hanging, maybe growing up. To soften it and make seem less linear. You have to widen it visually I think x

Forget the thing about the coving! The door frame is normal level! I just had to back track to check. You still don’t have to have coving, it used to be to cover the join between wall and ceiling but that’s not so necessary these days presumably because of better plaster? You can make a good join. Coving would be fussy in this room, completely unnecessary above and at the back of the wall units.
You might find the removal of the wood on the ceiling more destructive than anticipated to the tops of the walls so new plasterboard ceiling and skimming in plaster of all might be necessary. White with some cleverly hung / mounted plants would be my advice. Could even be herbs xx

Here are my thoughts. Before you go to the trouble of removing the ceiling, have you considered painting it? I would put filler in the grooves then paint it white. Invest in a modern bar ceiling light, not spotlights, install under-cabinet lighting if you don’t already have it and use a battery lamp on the table when dining. I would paint the walls neutral as well as the doors and window surrounds and add colour with a new splash-back, door mat and so on. A double waste bin will keep things tidy and can the tv cables be hidden? And I’d keep your window ledges free to let in as much light as possible.