I recommend checking out Michael Bazzell's "Extreme Privacy Mobile Devices" guide on creating an anonymous phone using grapheneos. In summary, (1) get service through mint mobile using an alias name, and (2) port your cell number over to a voip carrier (I use jmp.chat) so that you never have to give out the cell number attached to the actual cell service. I don't even know what cell number is attached to my mint mobile service.