The fastest, most effective way of getting that biodiversity you need is to order live rock and sand from someplace reputable like
https://tbsaltwater.com/ (They'll be shipping again in November.) Otherwise, you're kind of piecing it together — which can definitely be done, it's just more work (and may not get you everything). The flip side of that is that with live rock and sand, you don't know what
else you might be getting.
Either way you go, it seems like adding copepods to get colonies started is always helpful.