I would add one more thing (and this is maybe for down the line): There's a use case for duplicating envs beyond just development environments. There's a lot of value in cases where the SaaS product itself requires on-demand environment generation. Where customers of it need staging instances so they can see what config changes are before they merge to production. Obviously in that case, you're treating an actual product like a terraform provider, and the API's of that product as resources. I would explore that down the line because there's a lot of value in a service like that.
FYI, I would love to get involved any way I can to help you guys grow this. Let me know how I can help! mailto:ramish@ualberta.ca if you're interested :)