Interstate (JCI) went in the toilet some years back. That's why we switched here.
VAG OEM and replacement batteries are very good. They can be supplied by several companies. Entertec, Varta, and I even had a 2019 Jetta here with an Exide battery under the hood from the factory.
Oddly enough, Varta was part of JCI, but that name has been changed to Clarios now.
In any event, the OEM has a specific datasheet it must meet, and VAG's requirements are as good or better than some, so the dealer stuff is good. And add to the fact that they are competitive on price, all the better.
They are a common case size battery, so if you absolutely need to, you can find one that will work almost anywhere.