I use a bike-boom era (1980) 10-speed road bike for all my commuting needs. It has 27"/1-1/4" tires which are skinnier than most 26" tires but not as hard-core small as some of the road-bike tires I see.

I've carried some significant loads on this bike with no problems. Obviously staying alert and avoiding potholes is a must, but I've hit one or two and didn't damage the wheels, or pinch flat so they're not super fragile either.

Most of my morning ride-in is all paved MUP or roads, however in the evenings and on just-for-fun rides with my gf I quite often take it onto the loose gravel/packed dirt paths in the area and haven't had any real problems. Just make sure you know to expect the front wheel to slide a bit on things like gravel and adjust your cornering style accordingly.