Here are the ones I use:
Skyr Icelandic yoghurt with frozen blueberries and a small drizzle of honey (optional) with 3-4 walnut halves chopped up and scattered on top.
Skyr with frozen raspberries and a tablespoon of low sugar granola sprinkled on top
homemade porridge with 30g oats, half water, half semi skimmed milk to cook in, a sprinkling of cinnamon and nutmeg, then either half a banana chopped up and cooked in it to sweeten it, or a cup of frozen blueberries.
Granary bagel thin with an egg on top, poached in water.
Two eggs scrambled with just a bit of milk, and smoked salmon
Wholewheat or granary bagel thin spread with low fat cream cheese and sliced tomatoes with salt and pepper and fresh thyme.
Bagel thin toasted with half tin of low sugar baked beans
Citrus fruit salad: pink grapefruit, orange and tangerine with some fresh mint leaves.
Grilled streaky bacon, cooked until crisp, with grilled tomatoes sprinkled with salt pepper and garlic granules.
Most of these aren't low carb but I find mixing up low carb with carb but low fat keeps me on track better. It's easier to low carb later in the day with grilled fish or meat and veg. First thing I often find rich food hard to stomach. If you want low carb, some of the low carb protein breads you can buy online are delicious. But expensive.