custom grains with gitfs

[bradawk1]

I've been searching the Internet, but so far have not found anything relevant. We are using gitfs. I created a branch to track our changes in accordance with the RHEL 9 DISA STIG. In the customgrains.py, I removed a CentOS 7 related grain and added one for CPU manufacturer. I'm trying to figure out the correct way to test this branch? If I go on one of our RHEL 9 test servers and run:
salt-call state.apply saltenv=745-rhel9-disa-stig
I receive errors based on grains. If I run:
salt-call saltutil.sync_grains saltenv=745-rhel9-disa-stig
then a
salt-call grains.item cpu_manuf'
returns nothing.
What is the proper way to test a git branch with custom grain changes?