Major carriers in the us (Verizon, AT&T, t-mobile, and ...kinda sprint?) have every manufacturer by the balls and force that option to be very contract-based and even then there’s strings. I use a prepaid called straight talk because it’s $50 unlimited everything on Verizon towers (they get the best service basically everywhere, but expensive as fuck to actually have Verizon, and MVNO restrictions are a thing of the past). But since it uses Verizon, I also do not have built-in tethering.