Today I spotted on the map an odd sight: a non-military 1961 KC-135R. Weird.
The plane is registered via a trust, but it is owned and operated by Meta Strategic Mobility and it appears they have a fleet size of 4. Further research shows that their planes are formerly of the Republic of Singapore Air Force.
If you're interested in tracking the four Meta planes, you can do so with this one link: https://globe.adsbexchange.com/?icao=a75334,a75aa2,a7496d,a75aa2.
So what's the deal with privatized a2a refueling? Who/what are they refueling? Well, I found an article saying that this company, Meta, signed a contract with the USNavy to carry out refueling operations for training purposes. It does appear that there are other privatized companies doing the same thing.
Are there other companies doing it? Omega Air Refueling is another company that is doing the same. The database I use shows these planes as being registered to Aircraft Endeavors LLC. If you want to track all the Omega planes, you can with this link: https://globe.adsbexchange.com/?icao=a822e1,a82698,a8392b,a96fb1,ad9470. It looks like they're operating older DC-10's off the coast of Myrtle Beach.