using existing sims to transfer byop phones

[davemp404]

Getting a oneplus 7T and want to transfer my wife's iphone 5s to my pixel 4a. We are both on Verizon network and the oneplus says it works on verizon's LTE network only (since 3g is going away end of this year it shouldn't matter?). Was going to use a new verizon sim to transfer the pixel to the oneplus.
After oneplus transfer is complete, can I use the existing sim in pixel to transfer from iphone or should I just move iphone sim to the pixel?

[TracFone - Maria]

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