Is it technically possible to support wireless power transmitter coils other than A1 or A6, such as A3, A4, A5, B1, etc. if we use multiple P9030’s?

IDT has solutions to address coil configurations requiring a 10-20V DC input.  For multi-coil designs, some additional passive components (switching FETS) would be required, but only one P9030 transmitter IC is required as long as only a single device needs to be charged at a time.