Mint Mobile is an MVNO that runs on the T-Mobile network. Google Fi is also an MVNO, but it runs on T-Mobile, Sprint, and the regional US Cellular. Since T-Mobile merged with Sprint, the coverage of Mint Mobile and Google Fi will eventually be similar once T-Mobile converts the Sprint towers, which is in progress.
If you live in an area where T-Mobile is weaker (rural areas or areas outside of metropolitan areas), AT&T and Verizon will provide more consistent coverage than both Google Fi and Mint. AT&T is GSM-based and will work on the Librem 5 and the PinePhone. Verizon is CDMA-based and might not fully work on these phones.
AT&T Prepaid is currently offering an unlimited plan with 22GB of unthrottled 5G and 4G data for $50/month plus tax with monthly billing. There is also an offer for 8GB of 4G data for $25/month plus tax with annual billing.
GSM-based networks still seem to be the more reliable option for Linux phones, but it's good to see that Verizon might also be compatible with some effort.
If you live in an area where T-Mobile is weaker (rural areas or areas outside of metropolitan areas), AT&T and Verizon will provide more consistent coverage than both Google Fi and Mint. AT&T is GSM-based and will work on the Librem 5 and the PinePhone. Verizon is CDMA-based and might not fully work on these phones.
AT&T Prepaid is currently offering an unlimited plan with 22GB of unthrottled 5G and 4G data for $50/month plus tax with monthly billing. There is also an offer for 8GB of 4G data for $25/month plus tax with annual billing.
https://www.att.com/prepaid