I have the Galaxy S10 and also have this problem. Verizon disabled the feature for their Samsung phones, giving no explanation why. I also created a thread. Lots of users are switching to Tmobile due to this. I am considering it as well.
We are new to Verizon (after 24 years with Sprint) and I was surprised to see/experience that Verizon disables the call and text on other devices feature (as well as RCS, except for a few phones.)
When we signed up for service I purchased the S21 Ultra at the Verizon store and my partner kept his unlocked S20. My S21 doesn't have the feature available, whereas his unlocked S20 does. I don't understand why Verizon disables this feature for their locked phones. It's such a convienent feature to have and I miss dearly!