Moto G5 Plus solution
GOOD NEWS for Moto G5 plus owners.
I've been running all the above mentioned circles trying to activate my Moto G5 plus on TPO CDMA.
Found a simplest solution: order SIM kit 3 in 1 for that phone from TING.
Got it, installed it - phone is activated.
It will cost you $9.99 - but it works.