I posted my landing page in a Facebook group and got 80 visitors and 6 registrants

There are many suitable alternatives for where to launch a product, but it is good to do some idea validation experiments before the product is ready to launch. The landing pages that invite visitors to sign up for a waiting list are common idea validation experiments, but it seems to me that there are few suitable alternatives for where to publish the landing page URL, which may make the results of this experiment insufficient or unclear.

I am working on building a tool that makes it easier for ChatGPT Plus users to add actions to the custom GPT, so I made a landing page that explains the problem and the solution and calls the visitors to submit for a waiting list, then I wondered where is the appropriate place to invite interested people to visit this landing page.

I initially published it on a Discord server related to ChatGPT with 6000 members, but the engagement on this server is low in general, and I only got cockroaches.

On Facebook, most groups prohibit promotion and link posting, but I found a group related to ChatGPT where posting is open and the link can be placed in a comment. Although it has more than a million members, the engagement in it is also low, perhaps due to the spam it contains. I posted in this group inviting those who are having difficulty adding actions to their custom GPT to visit my landing page. I got about a low engagement with my post, 80 visitors to my landing page, and 6 registrants on the waiting list. When I sent the registrants an email (using Brevo), Brevo did not record any opening of the email. This experiment seems to be a negative indicator.

I would like to find a group that includes a good engagement with members interested in custom GPT actions, so the results of the experiment could be a good indicator of the success or failure of the product. It seemed to me that some Reddit groups are good, but I do not have enough karma to post and it seems that there is a restriction on my account as I always get error messages and my comments do not get any engagement and I cannot post even in groups that do not require karma.

Now I do not know what the next step is. Is the idea a failure and should I forget it? Are there better ways to do experiments with landing pages? Should I consider different types of experiments? Should I just build the product, launch it, and see what happens?

I hope the indie hackers have any useful insights on this!