For one thing, I just want to say that this is 110% a legitimate, reasonable, and constructive question to ask here! I can’t speak for Stephen, but - as a relatively longtime user of his library - I think I might have some worthwhile touchpoints depending on how long you’ve used Drafts, itself.
I know you sorta mentioned it, but one great comfort you can take regarding privacy in Drafts is that - basically without exception - actions with external integration have to ask you for credentials before they can do anything via a very specific type of dialog, and you can always see a list of said credentials (the titles, anyway) in Settings (Gear Menu) ⇨ Credentials (It’s the sole entry under the “Services” subgroup.) You’ll find that you can revoke any of them at any time if you feel unclear about what’s happening.
As far as auditing is concerned, Drafts’ native Action Log is very dependable as long as you make sure the actions you’re using aren’t explicitly configured not to log. If you’ve got the time, the TAD library actually includes some very impressive “Advanced Logging” capabilities - though I must admit I’m basically just getting started with them, personally.
I know my commentary was not solicited but my logline for Drafts when speaking about it for the first time is specifically “I trust Drafts more deeply than any other software I’ve ever used.” Perhaps the biggest contributor to that is how well documented it is. (Remarkably, the TAD Library is, as well.) The second is how patient and open Greg and this very community have been with me. (I promise you I’ve asked far, far less appropriate questions here and gotten away with it lol.)
That said, welcome! I hope that was at least somewhat useful lol.