>only supported 3G - a networking standard that has been turned off by the major carriers.
Remember, the US is not the world. What major carriers do in the US is not necessarily a global fact. Where I live 2G and 3G is still a fallback if 4G or 5G doesn't work. It will continue to be that way until 2025.
>If your motorcycle only supported leaded gas could you use it?
Google lead replacement additive or think about whether the engine could be rebuilt/replaced on a motorcycle. I certainly would prefer an engine rebuild/replace over replacing a modem in an iPhone 3GS.
>the iPhone from 2009 was an iPhone 3GS, it had a 320x480 screen, 256MB of RAM
The iPhone from 2009 wasn't that impressive in specs compared to other phones at the time. My even older 2.5G dumbphone had higher PPI on the screen and could run useful j2me apps. In 2010, the iPhone 4 came, had a 640x960 screen and 512MB of RAM. The fact that the specs could be doubled within a year shows that the earlier 3GS wasn't pushing anything spec wise.