If you have LTE or even 5G in the house/apartment, you don't need any additional antennas or anything. Just Gigacube or the equivalent from Telekom and that's it. Alternatively, a router with a SIM card (like Fritz LTE) and just insert a data card.
Do you / does anyone have tips regarding data plans?
We found an unlimited plan at Telekom for €75 / month, but it has a 24-month contract. o2 Homespot says "not available" at our address. Instead, they offer us the 2Mbit DSL package. :/
I am very inexperienced when it comes to data plans. Who can recommend one (and maybe also hardware?) to get the maximum out of the mobile network?
I checked the map again, our address is in the LTE/4G area, but right on the border to 5G. We are house no. 12, and house no. 6 would have 5G. So I probably can't count on 5G, but 4G is not too bad compared to 2Mbit DSL.