I've told HD, Lowes, and Grainger, that if they work with us to set up our inventory that they would get all of our purchases. They all said it was a great idea and never heard back from any of them.
They can't manage their own variances for an infinite # of reasons. You don't want them on yours.
When there is a variance, who's fault would it be ?
There are numerous low cost inventory tracking and work order tracking apps which include parts mgt. Most only cost a small monthly service subscription fee per user.
Click software is well known.
Mobiworx is just as good.
GE has a servicemax.