One-way partner awards have been coming to Alaska already for some time and now American Airlines ones are bookable online.
Both American and Delta awards are online for one-way travel, but booking Delta makes no sense, as you are charged for return travel anyway.
Here’s example for one-way award search from Lima to Miami area
You can get American Airlines flights for 17.5K in economy and 30K in business class (shows as first on Alaska’s award search). Awards on Delta are 35K in economy and 60K in business.
Here’s return award search from Seattle to Miami
You can mix and match American, Delta, and Alaska flights. They price correctly at the return level.
It was about the time for Alaska to introduce one-way awards. I truly hope that they bring these for all of their extensive partner network and make them bookable online.