I am trying to create a sensor that will display how many updates I have on my HA install. Core and add ons etc.
Any help with be greatly appreciated.
Not sure, if it shows exactly what you’re asking for, but have you seen the SPOOK integration?
Spook 
a scary powerful toolbox for Home Assistant.
This kind of shows it, it shows how many things can be updated whether they have an actual update or not, I just need to know how many add ones etc have a pending update to install. If I make sense