I get these sugar free vanilla creamers on Amazon. So far I've liked them better than the little half-&-half cups which you can also find on Amazon but they're both low carb and good shelf-stable choices for coffee. I've tried powdered heavy cream but it doesn't work very well for drinks: It's clumpy and doesn't mix well unless the drink is super duper hot; but if you can use one of those little battery operated drink mixers at your desk it might be an option. You could probably find powdered coconut milk in an international grocery store (it's used in Thai or Indian food sometimes) just make sure the one you find isn't full of sugar: Coconut can be a nice flavor for tea in particular and not bad in coffee but is definitely coconutty tasting. There are a couple of keto-specific creamers out there which appear to be mainly made of ghee and coconut oil, but they're really expensive and I haven't tried them.