Some cars with frunks also have issues with them being an additional vector for road noise to impact the cabin, which is already an issue in EVs due to nothing

Some cars with frunks also have issues with them being an additional vector for road noise to impact the cabin, which is already an issue in EVs due to nothing being masked by ICE noise. That's certainly a solvable engineering problem (and Tesla has made changes in successive generations to try and improve the situation, for example), but the insulation/padding required further impacts the usable space. In any case, the EQS likely has the quietest interior of any EV to date.