WiFi from a satellite is actually impossible, due to a number of issues. Regulation wise WiFi only works because of the ability to have low power unlicensed devices, for it to work in space it would require a much more powerful system. The limit is 4 W EIRP. Furthermore, the movement of the satellite will create Doppler shift of the frequency, which will make the bandwidth too high to be supported.
What will actually be done I believe is that each device that wants to use Starlink will use some kind of a dedicated antenna. It might be like an ISP, using an antenna to send internet to a single house, or it might be something broader to send it to something like a Cruise ship, or even ISP to ISP links via satellite.
The frequency of Starlink will be above 10 GHz, well outside of the band of Wifi. At that high frequency, it is possible to have a hand-held device that could receive the satellite signals, as the antenna will be small.