I see ads all the time for shit like consumer Cellular, mint mobile, stuff that rents time on Verizon towers and sells you a plan for like half the price.
I’m trying real hard to de-Xfinity myself but the cellular plan is the cheapest of all the major companies. Yes, I know they also piggyback off the Verizon network, but at least they have 24/7 support
Have used various MVNOs for years with no real issues. US Mobile has been pretty good and can use TMobile or Verizon and soon AT&T.