A TEC only has an efficiency in the order of dozens % to single-digit.
An airconditioner can move heat around at a EER at 2.6 (W/W) or more. => 1kW input, 2.6kW cooling out.
Its literal order(s) of magnitude more efficient.
Only thing to avoid is floor standing AC units with a dryer hose out the back. Those have bad efficiency and need to have the water tray manually emptied all the time as they run.
Unfortunately, in many countries split aircons are very hard to get for DIY installations. The only ones I see are for caravans and campers which are only 400-500W, from 12V DC, and still cost 600 euro.
In EU we also don't really have the classis sliding windows that can hang an window airconditioner like in US, unfortunately.
There is actually a mod for portable aircons, called a dual airhose conversion.
Normally those units operate so poorly because the single air outlet forces air outside the room, which creates an underpressure, and thus you will suck in outside air from cracks etc. in windows/doors. That's the outside air you want to keep out.
By redirecting the inlet airflow for the condenser to a second airhose and drawing fresh air directly from outside, you can minimize this erroneous airflow and improve the efficiency quite drastically.
The most important thing is to watch out for overheating of the compressor/condenser coils as it now draws in hotter air from outside (which in hot climates is more challenging in the relatively modest "30C heatwaves" we have here). Don't go too restrictive on the inlet. I took a 150mm hose, just as big as the outlet, and did some temperature checks before I finally commissioned 2 units in my house. (I rent so this is my only option, unfortunately)
Emptying the condenser water is a waste. Many airconitioners have a drip tray that will 'overflow' into the condenser side helping it cool down extra through evaporation as well. I even saw some guy intentionally adding extra water to the condenser after a dual hose mod, because otherwise the aircon would hit thermal shutdown on really hot days (up to 40C here).
I've no idea why manufacturers create these portable aircons with a single hose from the factory.. It's not like 1 or 2 hoses is such a dramatic installation difference. Presumably people don't want to deal with air hoses and covers/seals at all.. (E.g. see BS like this:
Evolar EVO-ES9000)
A few years ago I did see a few airconditioners with dual hose.. but in my ignorance I didn't get one. Since then they have gone 'out of fashion'. I only know of 1 mobile airconditioner available locally that still features this concept 'off the shelf':
https://www.inventum.eu/klimaat-comfort/airconditioners/ac127wset/But only with the optional booster kit. But that unit is not cheap.. the aircons I got are also 12kBTU but I got them for 120 euro as new in open box.