What to do with a spare 1/2 gallon?

I brewed up a Witbier a while back to use as the base for a fruit beer.  After primary, I cold crashed, then racked the Wit onto the fruit puree for secondary.  After racking I was left with a half gallon of very nice Wit, which I captured in a half gallon brown growler and stuck an airlock on it.

How would you go about carbing this up to enjoy?  Can a small growler handle bottle conditioning pressure?

Throw in 1-2 TBSP of table sugar and cap it off. One TBSP will carbonate a growler fairly well, and two will carbonate it a lot.

Some growlers are not safe to carbonate in. Do a search for carbonator caps.

I got a package of fizz drops that if I have more beer than I can get into my keg I bottle a few with them.

What about the caps that have ball lock connectors and screw on to 20 fl oz and 2 L pop bottles?

That’s how I roll.  I call it “rescue beer.”  I get to sample some of the beer right away and let the rest of it carb up properly.  I have no complaints about mine, other than the initial expense.