I live in a cheap apartment with a cheap freezer-in-a-fridge - the kind where you open the fridge door to get into the freezer.
HATE.
I’m tired of defrosting the damn thing. Is there something I can apply to the metal interior of the freezer bit to retard the ice crystals? Oil, alcohol, antifreeze…anything?
No. Stop the introduction of moisture, and defrosting ceases to be an issue. Then again, you can’t open the door, as that admits moisture.
What about hanging packets of silica gel to absorb the moisture?
Those would quickly be overwhelmed by the sheer volume of water involved. The best you can do for those freezer in fridge units is ensure that the freezer door closes completely and forms a good seal.
It also helps not to overfill it so that air can circulate.