The hardware is already there, someone just needs to mod/hack that in.

https://en.wikipedia.org/wiki/Electric_vehicle_warning_sounds

In fact, it looks like we were going to get custom sound effects but the DOT killed it:

https://www.federalregister.gov/documents/2022/07/13/2022-14733/federal-motor-vehicle-safety-standards-minimum-sound-requirements-for-hybrid-and-electric-vehicles

The agency has chosen not to adopt the remaining portions of the NPRM, including a proposal which would have allowed manufactures of hybrid and electric vehicles (HEVs) to install a number of driver-selectable pedestrian alert sounds in each HEV they manufacture.