> I wonder how practical and safe it would be to build fusion pants close to city centers in order to harvest the excess heat for district heating

The cost/benefit for doing this seems pretty similar between fusion as gas power. We don't usually do this with gas, so I guess it's probably not viable for fusion.

Combined heat and electricity production is uncommon in the US, but much more so in Europe. Especially in the Baltics, Scandinavia and the Netherlands, non-CHP generation is rare. Related: higher energy cost, and elaborate local heat distribution networks.