You asked about secular 12-step programs, not secular alternatives to 12-step programs, so I presume that's what you're interested in. As noted above, you might check out the Secular 12-Step Recovery sub-forum here. There is a lot of good stuff at
https://aaagnostica.org/, and if you google "AA Agnosic" you'll find much more, including some local meetings depending on where you live.