This app was mentioned in 3 comments, with an average of 2.33 upvotes
This one seems good, also offers fingerprint signings.
https://play.google.com/store/apps/details?id=com.glykka.easysign&hl=en
SignEasy has integrated Nexus Imprint.
https://play.google.com/store/apps/details?id=com.glykka.easysign