The Motorola One Power and Moto Z3 Play are fairly recent releases from Motorola, having debuted earlier this year. Both phones have now had their kernel source codes published on GitHub, meaning that custom development for them can now properly begin.
Unlike most Motorola kernel source releases, the Z3 Play's took a while to arrive. We complained about the Moto Z3's source code having taken a bit long to get here, but the Z3 is actually a month newer than the Z3 Play. The One Power was fairly quick, given that it's based on the Pie update that started rolling out a little over a week ago.
If you're a developer for either phone and need to access the source codes, you can do so via the links below.