Here's an excellent source. A repository of FreeDOS-compatible freeware and OSS software. No abandonware: https://clasqm.github.io/freedos-repo

Interesting dev, too, he has his own other DOS-related stuff available as well, e.g. in qbasic. See his main github.io page.

EDIT: From the linked Github repo, another great resource. "Reviews, descriptions, links to 1000+ DOS programs. Freeware and free-for-private-use shareware listed ... since 1994": http://reimagery.com/fsfd