Possible to use w/ Gravityforms + Different email marketing?

Hey, I totally love your plugin (see earlier support request by me), and was wondering if it was at all possible to somehow make a workaround to use FormsCRM > Gravity Forms > an email marketing company not listed in your drop down (when setting up a feed)?

I have a client who wants to stop using Mailerlite and use Beehiiv instead. Beehiiv seems really flexible for all kinds of different use cases, including easy peasy API keys (creating and using). They have their own form maker, but my client wants to keep using Gravity forms so that the subscribers still “start” with her website first before getting integrated elsewhere. She wants ownership of all content, rather than solely relying on a separate company.

Is this at all possible with your plugin, or did I just ask for the world from a free plugin that does not owe me anything other than to keep staying awesome. yes, I am asking the world from a free plugin. Sorry! But if there is indeed a way to integrate beehiiv’s API key with your plugin, please tell me how!

Love always, Beatty