Scheduling algorithms are not standardized, so it is up to each vendor to choose what kind of scheduling policy to use and how to implement it. The implementations are proprietary, so we don't know what is being implemented.
Since the MAC scheduler implementation is usually proprietary, one option is to examine it within a simulator. The following two links have some information on NetSim's MAC scheduler and the PFS algorithm used:
1. How does the 5G MAC scheduler work in NetSim? https://support.tetcos.com/a/solutions/articles/14000109040/edit
2. NetSim 5G documentation (v14.1) on the PFS scheduler: https://tetcos.com/downloads/v14.1/5G-NR.pdf (Sections: 3.8.2 and 4.4)