First.. longtime Rachio sprinkler controller user, and happy customer.
I have purchased a few different watering solutions for potted plants where a controller pumps water from a bucket through a hose or network of hose/emitters to potted plants. This is useful for cases where one might be out of town for some time, and need patio plants watered during an absence. I would rather not use a hose timer, as this requires an always-on hose bib, and can be problematic if there are leaks. Most recently, I’ve been using one of these: Amazon.com (Rainpoint watering system). I’m on my third one, as they seem to be pretty poorly engineered (software mostly, but also hardware).
Given the solid engineering and good product design I’ve experienced with Rachio, it seems like something like this could fill a gap in your product lineup. My thinking is a solution for those who don’t have (or don’t want to have) a hose bib available and ‘on’ 24/7, and whose watering needs are modest, like 1-2 dozen potted plants, either indoors or out. Water would be pumped from a 5-gal bucket (or similar). In my case, I fill the bucket about once every 2-3 weeks.
The app could possibly be integrated in your current controller app, reducing the need for yet another app.