Gut an AC from the dump. Replace the condenser with a tube in tube heat exchanger, using your cold water as a heat sink. Brazed plate HX if you’re feeling rich. Replace the cap tube with a TXV for better load tracking. Recharge with R290.

T Sure this is even further beyond your skill level but is the best possible way to use a source of cold to chill your apartment. You can locate it anywhere convenient, not just by the window. You could likely get a COP over 5 and be discharging the water in a fairly modest stream at around 30-40C.