> This is not some suspect newfangled technology.

Is there somebody that did a practical small scale run of this?

Hydrogen storage has a huge amount of issues that natural gas doesn't. By its face value, storing hydrogen in a natural container doesn't look viable.

Yes, it's been done it least three places, to act as a hydrogen buffer for ammonia production (decoupling the steam methane reformers from the ammonia plants for greater operational flexibility.)

There are also large scale plans in progress to do it for grid energy storage, for example in Delta, Utah. The salt formation there has enough space for 100 cavities that could, altogether, store enough hydrogen to power the average US grid electrical energy consumption for about a day.