Outreachy, a nonprofit program that supports diversity in FOSS, connects interns with open source projects in a similar manner to Google Summer of Code… and they are currently taking applications from open source projects that want to participate in their May-August 2021 round!
Interested projects will need to supply a mentor (or two) to support the intern, and unless you’re a humanitarian FOSS project, may also need to provide funding ($6,500 per intern). That said, you may be able to apply for funding support from the Outreachy General Fund.
To learn more and apply: Call for May 2021 mentoring communities
To share the opportunity: https://twitter.com/outreachy/status/1350159346957598720
While I’ve personally never participated in Outreachy, I have extensive GSoC experience and have collaborated with the Outreachy folks–so I’m happy to answer any general questions folks may have. For specific questions, I recommend reaching out to them directly