I also have a window like that in our shower - it may, but doesn't normally get wet from the shower. I have put in a thin venetian blind in white (made from plastic) very cheap, under $5. I am in process of making an puffy austrian blind to hang above the window, for a bit of colour I am making it from a shower curtain). It will be there for looks, I may never pull it down. The venetian gives privacy and blocks the light a certain amount.

Something to consider with roller blinds- The blockout ones can really block the airflow in Summer, and if you do leave the louvres open, the slightest breeze will cause the bottom rod to bang against the window frame. You can fix them so they don't do this, but again you have the reduced airflow.....which is why you have louvres in the first place. We have the same problem. My son's bedroom. He seems to have adjusted to no window coverings. Luckily we have no privacy issues.

Your external blinds, or external shutters are best to keep morning heat out. If the air Con in window is staying then external blind as you have now will allow air flow to ac. You don’t have much wall space to draw curtains back off the windows and would block ac so if you want to keep the view out during day internal blinds to supplement the external are you best option, with 2 for the window with the ac.

Different rooms will need diff solutions. You can hang blinds on the windows themselves or mount blinds or curtains on wall above window, just make sure they are mounted out far enough for the window to be tilted open and with curtains that you can draw them back clear of the window to allow it to swing open. Looks like you have wall space in the living pictured.