Will these things actually dramatically decrease the lifespan

using a battery decreases the life of the battery, yes

no one gives a shit that the radio and your dash uses up your battery's lifespan tho

Will it decrease the lifespan? Yes, simply by existing the lifespan is diminishing. Drastically? No.

with the alternator running, it's unlikely to do any substantial draw. even if you had a usb type c connector with power delivery, most portable devices aren't going to take more than 15V @ 1.5A = 30 watts.

now if you run in accessory power a ton (or your car has always on DC outlets and you use it with the car off), or you charge something larger (e.g. 65W/90W laptop charger), that's bad for the battery. try to keep those devices only charging when the car is actually started and the alternator is running.

but most phones are going to take a top output of about 15W (5V @ 3A under USB Power delivery or 9V @ 6A for Qualcomm quick charge [many android flagships use this).

>>17717331
>your car battery
The battery will be fine. What causes trouble is the transformer in the gadget often feedsback undesirable spikes, eventually harming the ECU and other sensitive electronics.