I use a "mini-fridge" -- but surprise, it's both a cooler and heater! If you stuck your food in there in the morning, it will be warm and toasty by lunch time. Works well for me, and it's tiny so it fits easily in my office: https://www.amazon.com/gp/product/B08GS6ST3H/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1