I've been using the Pairing feature from Donut for over a year, as a great tool for the team to get to know each other. Adding onboarding is a huge win - we were "hacking" pairing to help new team members meet people, but now we can structure such a better process.
Onboarding was always something that was a bit haphazard, and Donut helped us put into place a more consistent experience and make sure we weren't forgetting any important information. It made it easier to setup a longer term onboarding program (1-3 mos instead of a couple weeks) and made sure everyone got the best experience even if their manager had other things going on.