Best option would be to remove and replace the patio paving

You can’t really place anything on top as it wouldn’t be stable enough, except decking as it sits on a raised platform. Decking doesn’t last long unless you go for hardwood decking. Ideally I would remove it and get a landscaper to lay something like Sandstone, which has a lovely rustic finish. It comes in several colours. They will dig down, add a base of Type 1 (rubble) then cement the paving in place. This is my Sandstone paving.

I was going to comment on this on your other post as I feel this would help ‘lift’ your garden & perhaps make you feel better about the house too. The best option would be to replace it but that is obviously quite an expensive option. Another (cheaper) option might be putting gravel down but I don’t know if that would work over the slabs or whether you’d be better off removing them first. Something light- coloured / cream /gold would work well to brighten the space & tone with your window frames.

Some large pots at the back of the house with greenery would also help.

A good pressure wash can do wonders I'm told. Certainly would help to give it the surface, and retaining brickwork a good clean whilst you are deciding on your next step.

Another option. As above with the cleaning and repointing, but leave out some of the pointing and plant so alpines in the larger gaps and maybe some thyme to soften it down, then add some nice large pots with evergreen shrubs or roses.