What is the current regulation on PCS leave?

It's not a regulation it's an HQDA EXORD or FRAGO. But it's not really worth spending an hour digging through Milsuite to find. Bottom line is that Army wide, PCS leave in conjunction with OCONUS PCS is currently unauthorized. It takes a General to approve it. You may take leave before your PCS then clear and leave. All the other leave policies like where, how long, how far, and vaccinated status, are all up to your local policy

Each base has different requirements - and each unit can have a different policy on leave requirements as well.

Here's Fort Drum's covid-19 policy that includes travel, leave/passes (based on what you have listed for your unit):

https://home.army.mil/drum/index.php/about/Garrison/public-affairs/coronavirus-update#:~:text=Effective%20immediately%2C%20fully%20vaccinated%20individuals,food%20preparation%20and%20dissemination%20areas%2C

I'm not sure how updated that is but it seems like they updated it since it says fully vaccinated people don't have to wear masks.

If your command doesn't want to approve that much leave, they don't have to. They really only need to approve leave for travel ultimately.

Your leadership should have your unit and post PCS leave policy on hand to refer to. Every base does have a different policy.

Have you been vaccinated? Different rules may apply.