Hi there!
I’m a beginner to HA, so bear with me please. 
Currently, I’m playing around with a Rollotron GW190 belt winder to integration into my HA solution.
What I have done so far:
Get the electrical stuff done, a Shelly Uni is connected to the GW190 to operate the push buttons the GW190 has. Thus I can maintain local usability (WAF!) and the Uni can operate the two directional push buttons too.
Control via Shelly WebUI works well. What I’m missing is an interlock feature that the Shelly 2.5 is having to make sure the UP and DOWN button are not pressed simultaneously, which would fry the belt winder motor, I guess.
My idea was to integration into HA to find a software solution for that interlock issue.
So far I have ShellyForHass installed via HACS, and I have a discovered Shelly device, the Uni.
The HA Dashboard presents me two buttons, obviously the two Uni Buttons for Up and Down.
The question is… how can I
a) establish interlocking so that either UP or DOWN is clickable
b) have a nice lovelace card for it like the Slider Button Card
c) let HA know how to drive the belt winder to specified % of opening the roller shutter.
d) Establish a “Stop” button in HA to halt a moving shutter, no matter if up or down movement.
Full open and full close is easy, I suppose, coz I will define the upper and lower endpoint within the GW190 itself.
A single short button signal would then be enough to drive the roller until full up or full down.
Thanks
Seba