I finally got the landing page ready. I built it with Wordpress (the Bridge theme - not the cleanest theme but it did the job once I got the hang of it) and it is super simple: I first mention the free newsletter (with a field and CTA to subscribe to it), detail what's in it and then I talk about access to the 💎 database.
I shared the landing page with a few peers to get some feedback and adjusted slightly.
Once I gave him the go ahead one of them shared it on Twitter (thanks Thomas!) and I shared it in a couple of places. This gave me about 75 subscribers in the first 2 days.