I am a very happy Nexus 5 owner in general. However, I have noticed that my (US version) Nexus 5 does not offer LTE in Germany --- at least on Tchibo as a carrier, who resells o2 (and maybe E-Plus, I am not sure). Now I am wondering whether the (unlocked) US version of the Google Pixel will have the same problem.
GSM arena has some specs for the supported bands:
2G bands
GSM 850 / 900 / 1800 / 1900 CDMA 800 / 1900
3G bands
HSDPA 850 / 1700(AWS) / 1900 / 2100 - USA
HSDPA 800 / 850 / 900 / 1700(AWS) / 1900 / 2100 - Global
CDMA2000 1xEV-DO
4G bands
LTE band 1(2100), 2(1900), 3(1800), 4(1700/2100), 5(850), 7(2600), 8(900),
12(700), 13(700), 17(700), 18(800), 19(800), 20(800), 21(1500),
26(850), 28(700), 32(1500), 38(2600), 39(1900), 40(2300), 41(2500) -
Global
LTE band 1(2100), 2(1900), 3(1800), 4(1700/2100), 5(850),
7(2600), 8(900), 12(700), 13(700), 17(700), 20(800), 25(1900),
26(850), 28(700), 29(700), 30(2300), 41(2500) - USA
Yet I feel unable to judge the significance of the differences, especially in terms of which bands carriers may be deciding to use in the future.