While I am strongly in favor of this, I suspect going fully open source might be 'too much, too soon' for ljdawson, as I'm not sure how used they are to open source practices.
As a gentler stepping stone that doesn't feel like giving all control away, I would suggest sharing the source code under the PolyForm Noncommercial license: https://polyformproject.org/licenses/noncommercial/1.0.0/
In other words, a 'shared-source' license that makes the code available for review, contributions and even copying, but disallows unauthorized commercial use. This provides a middle road between the fully proprietary protections Sync is used to, and the new open landscape of Lemmy & friends that it is venturing into.
For Redditors coming here who are unfamiliar with open source, here's a comprehensive introduction for those who care to find out: https://blog.erlend.sh/open-source-explained
In short, it is an essential antidote to enshittification.