look this guy what he did.
https://liliputing.com/2019/05/this-diy-smartwatch-is-open-source-so-you-can-build-your-own-but-you-probably-wont.html.
Its so hard to make something simple like this or make a decent reliable Phone-Watch.
Right now the trend from those Chinese Smartwatch makers is the Dual OS or Dual CPU, i really don’t see the meaning of this if not well implemented, if you are in bracelet mode you can’t get a phone call and its just a very low dim dial face and no touch screen,if you are in stand alone phone you can’t do nothing in the other mode,so just to get more battery life,so i will buy a Bluetooth bracelet watch for $5 skinny one and wear beside the watch.
I don’t think that they are going on the right direction even their costumers support they don’t even exit and thank God we have this community forums, i do own right now 3 of this Smartwacthes, and the only working properly but no happy with last update is my Lemfo LemX, beside the cheap build quality its doing ok,bought it because the big screen,but LPTS display,the flat tire and the simple design,those are the big contrast.
I know we aren’t gonna get any Bluetooth calling in this A7 SW any time soon, no mention and we don’t know what’s going on with the Open Watch project, hoping for the Watch-droid App the developer to stand on top this problem will see.
For i will keep login in this community helping and responding for what ever i know,in this coming month i will switch back to an Android Phone i will be in T-mobile plans and i will be try or using the Call forwarding feature that this company the only offered .
I will still looking for alternatives too,but we know the only is those Chinese SW,by the way they are getting expensive too.
Good luck in your feature buying and your life too. God bless this community.
Amen
The whole point of the essential mode is to be an extreme power saving mode. TicWatch’s version only keeps track of date, time, steps and 
rate, although newer Android watches are also keeping track of distance, kcal, and other cool exercise info, while still having lower power consumption. Most of these companies assume that your watch isn’t your only communication option. They assume, often correctly, that you have a regular- or smart-phone as well. It’s all about convenience and personal responsibility. If you are planning on your smartwatch being the only way for someone to get in contact with you, eg. exercising or something similar, they assume that you will have the common sense to have your watch fully charged or in a state that it won’t get too low before you get back to your phone. If a low power situation for your watch is unavoidable, it is also common sense to find a way to bring your phone with you, as a backup, like with an arm band or something. Please don’t disregard these watches that have the “essentials mode” just on the basis that, in that mode, you lose calling functionality. Almost all of these watches still keep track of essential exercise data, even if it’s only real-time and not always saved when you return to full Android mode, taking for granted that might be a cool option. Anyways, I hope this helps.