UPDATE: saving metadata as TMDL format now allows easy merging.
Power BI's June 2023 update introduced a feature that allows you to separate different objects of the PBIX into Reports, Dataset, underlying data file, Model.bim and the major benefit is that you can do Git Integration now with Power BI without relying on external tools for splitting the metadata and then making the changes and then combining back the file into PBIX.
Also, you can now link your Azure Repo to a PBI Workspace so that you can push changes using Git and they can be reflected there.
One issue that I face is that if you deviate from Main branch and add measure to let's say Dev branch and then add couple measures to Main branch and later try to merge Dev to Main the editor isn't able to resolve the issues and if you select 'Accept Both Changes' it gives you a model.bim file that contains incomplete code.
As you can see in the below image I have commits that are not on either of Main or Dev branches
If I try to merge Dev into Main
I get a model.bim file that shows incomplete codes:
If I accept both changes, I get:
The problem is the it is not easy to edit this JSON file, you could be meticulous and still end up with issues that you can't resolve. Hopefully this will be fixed in future.
One solution that I see is that you ask people working on different branches to create measures in different tables, while also making sure the measures are not named same, and later you can have one commit to move them in the same folder.