My two often need a 'starter' that can be shoved at them as soon as they've got shoes and coats off, as hungry, tired small children waiting for dinner to be cooked leads to disaster here. When they are only a bit hungry, we try for raw veg so that it doesn't spoil dinner, but other times we have to add in cheese, or peanut butter on crackers, or something like that – still reasonably nutritious, even if it doesn't have the variety of the main meal.
If necessary, I use a bit of screen time to keep the peace whilst they eat their starter and I cook. I figure twenty minutes of chilling with Cbeebies at the end of a busy day is really not the end of the world, and it goes off for the main meal.
I also prioritise fast meals, as otherwise the starter tends to become the meal, plus they get more tired and you still have to manage getting ready for bed afterward. Things like pesto pasta, jacket potatoes, stir fry, burritos/fajitas, pizza on a tortilla/pitta, and various things on toast are quick, or batching cooking or using a slow cooker can help.
On very tired days, stuff that is easy to eat – cheese on toast, pitta pizza, etc. When you're that small, using a fork takes thought and concentration, and sometimes that's just a bridge too far at the end of the day.