From our experience, I’d agree with @s.borello , you probably need to create your own families, mainly by modifying Autodesk familes or modifying manufacturer’s families.
In terms of symbols, despite numerous “standards”, every company I’ve worked for uses their own symbol library and so do manufacturers, so you would want to create your own library of generic annotation families which you can then nest into any family regardless of the source thus keeping consistent symbology in all your models.
Similarly you probably want to create your own shared parameters which you can load into families so that you can consistently schedule information.
Remember that BIM isn’t just about pretty 3D drawings, the information in families is important too.
For example, that MK family has some nice geometry to create a pretty picture but it has very little information in it (basically the manufacturer’s name and model number) and it doesn’t even have an electrical connector in it. So you could “borrow” their nice geometry, add a connector, add your own shared parameters and generic annotation symbol family and populate the parameters with your own data.
It might seem daunting but once you get into a routine you’ll be able to quickly modify families to your needs and there is loads of help available in this forum and elsewhere on the web.
In my opinion.
