I like in the United States and just switched to T-Mobile. Will this phone work with my mobile network? And does it have the Google App Store?

Yes, Google play factory pre installed

Please check below with your network provider

4G bands 4G FDD-LTE: B1(2100),B2(1900),B3(1800),B4(AWS),B5(850),B7(2600),B8(900),B12(700),B13(700), B18(800),B19(800),B20(800),B25(1900),B26(850),B28(700) 4G TDD-LTE: B34(2010),B38(2600),B39(1900),B40(2300),B41(2500)
5G bands 5G Sub-6 FDD: N1(2100) / 5G Sub-6 TDD: N78(3500),N79(4500)
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