I am considering a pinephone but have a question first

[ryo]

I contacted my carrier to determine whether they could support the pinephone on their network.

I'd not blindly trust that.
I once sat down at the nearest by SoftBank branch store for 2 long hours, they kept asking me what Android version my PinePhone was running on, even after saying multiple times it's Linux and not Android, only to then get a confirmation from HQ that SoftBank's USIM cards only work on either Android or iOS (they're not interchangeable).
Rakuten Mobile on the other hand worked out of the box, and another forum user once confirmed they could use on NTT docomo (which is one of the big 3 here alongside SoftBank, and Rakuten Mobile uses NTT docomo's network) as well.

If it's on the Wiki and it states it works with T-Mobile, then it should work though, since this list is compiled by actual PinePhone owners who tested it first hand.

Edit:
Thanks for reminding me about the Wiki.
I just updated a little bit based on the information above.