I changed out my house's locks from Schlage to Kwikset and did not save the pack of adapters they included. Was able to remix a lock blank from Thingiverse (linked below) and create a working adapter.
Printed in PLA+ with 100% infill.
Seems to be holding up!
Remixed from Thingiverse: https://www.thingiverse.com/thing:4310983
The author hasn't provided the model origin yet.