There’s a variety of possible explanations. When the G4 Plus was first introduced on Republic, only GSM (T-Mobile) coverage was available. If like the G6, you sourced the phone elsewhere and purchased Republic’s BYOP SIM that would have been GSM (T-Mobile). Until very recently all compatible phones sourced elsewhere, required they be activated on GSM first then moved to CDMA (Sprint) if possible. Now, though it requires a ticket, Republic is able to directly activate some compatible phones sourced elsewhere on CDMA.
What I’m trying to say is this has been an evolution and candidly continues to evolve. For me, being able to ask for and directly activate a SIM with potentially more appropriate coverage is less of a hassle than having only one option or having to activate with one SIM then switch to another. Is there room for improvement, certainly but, in my opinion, it’s getting better.
The reality is the more options one offers, though doing so introduces complexity the better. If Republic were only able to offer me CDMA (Sprint), I’d likely be gone because in my area GSM (T-Mobile) offers better coverage. Therefore, I’m happy Republic has the ability to offer GSM (T-Mobile) coverage.
I’m confident Republic staff will answer your ticket as soon as they’re able and likewise get you that CDMA SIM as quickly as they can. I’m not particularly confident an alternative provider would get their SIM to you faster, however, if you decide to investigate you need to ascertain whose network(s) they use for cellular coverage. For example signing up with Metro by T-Mobile wouldn’t help if CDMA (Sprint) coverage is better in your area than GSM (T-Mobile) because Metro by T-Mobile’s coverage is rather obviously T-Mobile.
At the end of the day unless you choose to source someone’s SIM locally, you’ll be waiting on someone to deliver one to you.