When 5G was considered high-frequency millimetre wave, most expected the short reach would make it a poor choice for rural areas. However, 22 of the 24 current 5G deployments are mid-band, which seems to have decent reach with Massive MIMO. (Limited data.) Sunrise saw an opportunity to go after a market that Swisscom was neglecting. It offers both fixed and mobile.
In June 2019, Sunrise is covering 80% or more of 248 villages. It was able to do that simply by upgrading the existing towers, not terribly expensive. (I'd guess about US$500 per customer but I don't have enough data.) It intends to cover most of the country by the end of 2019.
It's quite possible that the mid-band networks will be fine in many rural areas.