A new kind of not-newsletter: pointers needed :-)

Hi there,
I'm exploring a new concept - well I think it's new 😀 in which a reader will pre-pay for a certain number of emails, which will be sent on a non-regular basis.
The readers also have the option to decide not to receive the next email if the topic (which varies each time) is not of interest for them.

I have drafted high-level specs but fail to converge on which tool to start learning to do that. I've played a lot with Airtable and Zapier in the past, a bit with webflow... but I'm not sure at all these are well suited for my use case, especially the edition of existing records in airtable, which isn’t that easy. I'm also hesitating to enter into the looooong onboarding and training Bubble.io offers... What do you think?

The specs link is here // https://docs.google.com/document/d/1kWmjb3YYOsplElVGFDbTEjEJMPyz57fUgoqPIPBHvvQ/edit?usp=sharing

Thanks a lot for your help and feedbacks.