This is a problem. Not only by people around you but with video (both CCTV and mobile phones and anything in between). And it’s not even needed to see the screen as the pin entry is done with a static (always identical) numpad. I’ve also previously suggested ideas to make typing more safe and login more secure - options for the user to select which they would like to use. Audio/voice is not the only one. A pad that changes randomly, a full keyboard instead of numbers, hidden [invisible/unmarked areas for] keys/touches, adding rhythm/frequency/timing as part of the access key or possibility to make the pin/login dynamic depending on the time or something (a variation of a group of PINs depending for instance wich hour it is or is the minute odd/even etc. - make it as complex or simple as you want) - or even having a PIN+voice option (one or both could have dynamic variation). What @Gavaudan mentioned about the hardware keys could also be an option, but it could interfere if user is using services (or even login options) that require location or network in the background. Unfortunately I’m not an expert in this field and something this critical I’d rather see taken up by the manufacturer.
Btw. outside of these, there is also the possibility of using Librem Key for login too.