As of writing, most of those devboards you can see on the market come with an application processor without modem. The ones that really see huge volumes are the ones with integrated modems, e.g. MTK processors with modem or the Snapdragon series, interestingly you are not going to get any of them for $50.
Do you know why no desktop software is optimized for Xeon Phi, SPARC, POWER9? Because almost nobody plays with them.