My "posh" no effort, is buy some smoked salmon when it is on offer. Then get usually seasalt crackers or with pepper or whatever. put salmon on crackers, little tartare sauce and a squeeze of fresh lemon juice. Add glass of cold pinot grigio. Ah bliss. Biggest effort is sometimes opening the flipping salmon packet !. - and of course only 1 plate and 1 glass to wash up too.
When I am in the mood to cook and my back allows me, I make things like casserole, mince with lots of veg in it especially onions and celery, bolognaise sauce etc. Eat some and freeze rest into single portions. On rubbish day, with neither the energy or inclination, toss up between jacket potato done partly in microwave and finished in air fryer to get good skin, and add mince or whatever. Alternatively have 2 or 3 varieties of rice take 2 minutes and add sauce. When I am in cooking mode I do my own brown rice, but dont freeze that so the quick 2 minute stuff is for down days.
The other thing is what my father called "a concoction of fantatalam" which translates as look and see what you have in the fridge and either stir fry or make an omelete of the various things. They often taste very good but you can never make it exactly the same another time.