Google Fi

So Moto G5 was in the list if devices last year but is gone now. If I sign up a Moto G5 now, I would get to use all 3 carriers and not just TMo, right?

nvm, found answer...

You'll have full Fi functionality on these devices:
Calls, texts, and data on multiple 4G LTE networks (T-Mobile, Sprint, and USCC)
Automatic connection to 2 million secure WiFi hotspots
International roaming
An even more secure connection with Fi VPN
Designed for Fi models
Pixel 3 (Fi and Google store versions)
Pixel 3 XL (Fi and Google store versions)
Pixel 2 (North American and rest of world versions)
Pixel 2 XL (North American and rest of world versions)
Pixel Model G-2PW4100 (North American version)
Pixel XL Model G-2PW2100 (North American version)
LG G7 ThinQ (Unlocked North American versions sold by retailers)
LG V35 ThinQ (Unlocked North American versions sold by retailers)
Moto G6 (Unlocked North American versions sold by retailers)
Android One Moto X4 (North American versions)
Nexus 5X Model LGH790 (North American version)
Nexus 6P Model H1511 (North American version)
Nexus 6 Model XT1103 (North American version)

You'll have calls, texts, and data on T-Mobile's network as well as international roaming. You might be able to make calls or text over WiFi.

Moto Z Series

Z3 & Z3 Play
Z2 & Z2 Play & Z2 Force
Moto Z
Moto G

G6 Plus & G6 Play
G5S & G5S+ (running Android O or higher)
G5 & G5 Plus (running Android O or higher)
Moto E Series

E5 & E5 Plus & E5 Play
E4 Plus
Moto One (Android One)

Motorola One
Motorola One Power
All models must run Android 8.0 and have LTE bands 2 and 4.

Even if one can only use the T mobile network, getting $200 of service credit for Fi is still an excellent deal on the T-mobile network, which, assuming one doesn't need much or any data, works out to paying $40 dollars for a year of unlimited talk and text. $20 a month x 12 = $240 - $200 = $40. One can also, if still in effect, add a second line for $15 a month. Caveat: One cannot use GV#s on Fi the same as on other MVNOs or carriers, so if one is planning to do so, one should check the details about Fi and Google Voice #s.