A quick update here:
I managed to do what I needed using Zapier and my email list provider. Still, again, I would love to be able to do it inside Invision because, in my opinion, drip campaigns are great for (re)engagement and is a feature quite easy to code because most of the functions are there.
By the way had an issue with configuring the Nginx rewrite rules so Zapier can access the API, as it forced me to dwd a htaccess file, which we know is useless on Nginx, but that's a story for some other time 🙂
MediaDiGi's post in How to send a sequence of onboarding emails to users? was marked as the answer