I'm curious for your thoughts on this:

Whenever an app offers integrated TOR support, I would not trust it to use it for all requests as I had worked for a product that had introduced TOR but then forgot about maintaining it, so new devs connected to new servers forgetting about TOR.

Using TOR to completely proxy all traffic for an app should strictly provide more reliable privacy ... unless that doesn't play well with integrated TOR support which might choose a new circuit under certain conditions which the proxy cannot know when to do.