Yes & No:
Brakes squeaking like that can 'simply' be a function of the brake pads themselves. Some pads are formulated for quiet operation but usually at the compromise of more dust, e.g. German-mandated high graphite content.
Conversely there are pads that are low dust but usually at the expense of more squeaking, at least until they get warmed up; typically ceramic types.
The old adage with brake pads is performance-sound-dust: pick any two.
It can also be a function of environment dampness and thereby the typical flash rust on the front disc rotors that abates once dried/cleared by initial braking actions. Some vehicles with disc brakes periodically pulse the grip to ensure the rotors/pads are kept clear, but given that EV's are designed more for higher rolling efficiency the ID does not; and also because much of the vehicle's braking is accomplished by motor inertia.
The rear drum brakes being effectively encapsulated shouldn't be an issue. Note however that most of the brake-system braking (again, after motor regenerative braking) is accomplished by the front disc brakes given natural vehicle inertia.
My brakes do not squeak, nor surprisingly produce much dust (as did my prior VW AG vehicles). I believe the 20" wheels are well designed to ventilate and thereby the dust better removed? Many EV's have as their stock wheels very flat faced/non-ventilated wheels however to render lower aerodynamic rolling resistance (see Tesla base wheels). However my vehicle is garaged and typically dry so I'm possibly not the best peer for your situation.
Lastly note that brake pads perform best after being "bedded in", although most drivers don't do this and most have never even heard of it.
Since you now presumably have new pads/rotors/drums all around it will take some time for everything to again mesh properly.