In theory you can eat any low carb food you fancy for your breakfast but if you don't want to have to negotiate the stairs first thing, then that obviously limits you somewhat. But it's probably worth considering getting a small lunch box size cooler bag to allow you a bigger choice - you'd then have the option of cold meats and paté, yoghurt, various cheeses, etc.
Low carb muffins are a useful standby for any meal and you can make them sweet or savoury. You could also try a sort of "porridge" made with ground almonds, walnut or almond oil and a sprinkling of nuts - pecans, walnuts, pine nuts, pistachios.
Linwoods make various similar nut, seed and berries packet mixes which you could try too.
Robbity
PS Sometimes I find something oily or fatty as a bedtime snack/supper will then last me to around next lunch time or later.