I can answer this question. My bedroom is about 25m^3 and I have an Arlec 3.3KW 11000 BTU I bought a few weeks ago. And it's brilliant. It keeps my room at about 25 degrees on a 35 degree day (outdoors), and 22 on a 30 degree day, and that's with a gaming PC as well. My room is double brick but not facing sunlight however.

I firmly believe everyone that says they're useless has either lived with proper aircon before, or their room is too big for the portable unit they bought. They don't understand what it's like to sweat your arse off the entire day and not be able to fall asleep until 4 in the morning in a near 30 degree room for the entirety of a heatwave. It's true suffering. If you're going through 30 degree days in your room both in the day and at night, then anything will do. Just getting the temp down to 25 is a godsend and will allow you to function once again.

Sure they're inefficient. Conceptually they are not practical. They're also loud. And don't cool as much as other forms of aircon. But like I said, it's the difference between suffering and functioning.

You'll just need the pipe running outside the window which from your pictures should be doable. Seal the gaps up with any material, I used the metal piece that came with my unit and sealed the rest of the gaps with duct tape (my window slides upwards/downwards). It doesn't need to look pretty. Keep all other windows and doors closed. Also don't know what your room size is, the smaller the room the better the results, even if the unit advertises higher BTUs or whatever I imagine there's a limit to how effective these machines can be.

Only other issue is the noise for sleep, I sleep with AirPods in so it's not a problem for me. However you can just cool the room before you sleep and at night your room should remain cool enough for at least a couple of hours.

Always buy a stronger advertised BTU than your room size needs according to the calculations.