Smartwatch control via Bluetooth

I am doing some feasibility studies for a project and I am not an expert. I would like to control my smart device via Bluetooth Low Energy (BLE) from a device that is not a smartwatch. Nothing fancy, no application works with difficult tasks, no login / security, no external database, only some controls, such as turning on the screen, sampling and selecting the main functions built into each smart plan, let you speak by default ( e.g. email, phone calls, sms, music playback) and turn off the screen. Basically, instead of interacting with the smartwatch via a touchscreen, I want to interact with the smartwatch via BLE. Instead of using smartwatchs touchscreen as input source, I want to use another device as input source.The target OS is basically Android (but any other is useful to know!).

1) Is there any smartwatch that allows developing such functions in the smartwatch itself, without developing in the smartphone (i.e. I deploy some APIs in the smartwatch that handle the BLE module and implement the above tasks)? Can I connect a smart card with multiple devices, and also optional to smartphones? I know Pebble Time is very evolving and a solution like this could be (or will be) implemented, I'm curious if there are any other models that can allow this among Android and iOS devices.

2) Since I don't expect many devices to resolve what is set to 1, a smartphone app needs to be implemented. All I would like to do this app is a BLE connection between devices and smart watch. This means I don't want to implement a new email application or a new music player. I would like to use applications already present in the smartphone / watch, but control them from another device via BLE (i.e. instead of the smartwatch touchscreen). So basically signals / controls will come from device to smartphone, and from smartphone to smartwatch (and from smartwatch to smartphone, but because of the app I'm using). In short, I do not want to develop a proper smartwatch application, but rather a smartphone application,which controls the smartwatch (the application is not deployed in the smartvare itself). Are APIs like Smartwatch (swipe left, scroll down, select, etc.) basically the same exact APIs used by the smartwatch touchscreen driver) for Android and / or iOS?

Your wisdom and ideas are more than welcome (remember, I'm not a coding guru), thanks for reading! Dan