I have no issue using Verizon Messages (Message+) on a ASUS ZenWatch 2. The installation method of Message+ on the watch is a bit unusual, but once installed you can send and receive texts on your watch (at least until VZ breaks it again)! In case it matters I am using VS Messages: Last updated Apr 19, 2019.
To install VZ Messages (Message+) on the watch you have to follow these steps:
You did it, Message+ is working on your watch!