I don't know if this counts as a low-effort meal for you, but maybe French toast? I'm not sure if it's cooked differently in the West, but in CIS countries, all we do is mix eggs with milk, dip bread slices in the mixture, and fry them on a hot pan.
You can also mix cottage cheese with smetana (sour cream) or plain yogurt and add sugar. Done!
If you have a microwave, you can make a mug cake. There are lots of recipes online; some might work, some might not. I haven't made one in a long time, so I forgot the recipe that worked for me.
You can also just put a slice of sausage and cheese on a slice of bread and microwave it for 30 seconds. We call that a "buterbrod"

You can add a slice of tomato, cucumber, salad, or spread it with ketchup, whatever you like!
If I don't feel like cooking, I just stock up on cornflakes and milk and call it good enough for a few days
Hmm, instant noodles, supermarket pastries?
If you want a dessert (though it might need a little effort), here's one recipe: find cookies in your kitchen, no matter if they're old or not very tasty, and crumble them into tiny pieces. Add condensed milk and cocoa powder. Mix until you get a smooth texture. Roll into balls and put them in the fridge. Search for "pirozhnoye kartoshka" online for more detailed recipes.
What else... for a snack, you can just take a slice of bread, spread it with butter, and sprinkle sugar on top. Low-effort meals are all about improvisation! I also like spreading smetana on a slice of bread and topping it with jam.
Kids in daycare have a "soup" for breakfast made from milk and boiled buckwheat OR pasta (macaroni, vermicelli, etc). Hope this helps!