Thanks for all your work on this, fyi download link is 404
Until that's updated, in case it helps others, managed to dig up this one which appears to be a few revs newer than what's listed in the OP
twrp_albus_treble_3.2.2_r23_64.img
for the Motorola Moto Z2 Play(XT1710), by rahulsnair
https://androidfilehost.com/?fid=1322778262904007189
I successfully used this to install the LOS 15.1 linked in these forums, and it's working fine with os encryption (haven't tested backup encryption), still has the power button bug mentioned in the OP, and ran into a few of the other issues mentioned (maybe only mentioned in 32 bit thread) such as the Image not signed or corrupt
error/warning, but as he says beta.
I've tested usb otg, works, backups work though i haven't tried restores
cheers