No, Xiaomi's fast charger does not have the pd2.0 protocol, and uses the qc protocol. So switch cannot be used.
The switch fast charge is only compatible with the pd2.0 protocol, and the non-PD2.0 protocol fast charge head, although it can be charged on the switch, can not activate the fast charge mode, the maximum charging power can only be about 5W, far less than the handheld mode 12W, and can not reach the 45W required by the desktop mode.