The idea of mounting a directional antenna "high up" on a house (or paying someone to do it) for the purposes of receiving SMS 2FA seems wild.
You can also get antennas with suction cups. I have used this before to get 4G internet in a house with no access downstairs, by sticking the antenna on an upstairs window.
An outdoor antenna would be better, but yeah more of a pain. I guess it really depends on how badly someone wants SMS.
MOUNTAIN valleys, need to get WAY higher up than the top of the house.