I have a few Oto lawn sprinklers. I really like how they water and think that it is well designed and uses quality components. The App and support is great but there is no integration into HA. There is also one big issue with Oto . It relies on the cloud. If the internet connection to the sprinkler is lost it will stop watering. It also collects usage and diagnostic data. I really don’t like things that are cloudy and I’d prefer things to stay secure and local. For this reason I have been developing my own firmware for my Oto lawn sprinklers and intend to have a custom component and esphome support for my sprinklers. This way I can setup zones and schedules with HA and HA can provide rain and wind delay info or other automation rather then some cloud service. I am close to completing this but thought I would post here to see if there are others who may be interested in this. Please comment here if you are.
Love this. Would be very interested. Just got one and looking into the company developments recently I have little hope this will be supported in a few years.
I am testing my code now and nearing completion. I will post everything to github once complete. I want to make certain that my code waters at least as evenly as the original code which waters quite evenly based upon my testing. To upgrade to the new firmware physical access to the ESP32 uart is necessary. The good news is this is relatively easy to access. The bottom of the unit needs to be removed by unclipping a couple snap clips which is tricky but not hard if you don’t know how to access them. I will provide instructions and photos later. Once the bottom cover is removed there is a small rubber plug that can be pulled out gently to extend a uart cable that is plugged into to the main board. Nice of Oto to provide that access 
When I post to github I’ll provide a pinout and connection details for the first time flash. After that all updates should be OTA.
Would we be able to use the pouches again? That would be perfect.
Unfortunately no. In new units Oto has removed some of the hardware for the pouches. I think they ran into a legal issue. If you accidently spray someone in the face with water no big deal, if you do that with fertilizer or bug killer it could be a lawsuit.
I did see Oto released new firmware that has a kids play mode. I can try and incorporate something like that in the new HA firmware.
Okay, thanks.