If you can unlock the bootloader you can generally also reflash the firmware at will on the baseband, so you can replace it or modify it to remove any subsidy/carrier locking on the baseband side.

Unlocking the bootloader will also of course let you eliminate the carrier’s bloatware that they get paid to install and load onto it, including the things that they shoved all the way into the Android “non-disableable” list.

Tracfone called this “cellphone trafficking” all the way since the 90s when people would buy their loss leaders, flash ‘em, and flip ‘em to third world markets for top dollar.

https://stopcellphonetrafficking.com/