This. And devs with no family or medical expenses. A warning to anyone thinking they'll be fine taking a sabbatical without health insurance: you're playing with fire. Don't try it in the U.S.
COBRA is what I’ve seen people use when away from work, sometimes benefits continue for a few months.
If you don't have the resources to buy health insurance, you probably don't have enough cushion for a decent sabbatical anyway.
If you're young and healthy you can get a high deductible policy that will protect you in the event of a disaster for very cheap, in the $150/mo range. These are not the Obamacare covers all your pre-existing conditions without a healthcare screening plans.
Why no health insurance? Go on the ACA exchange and pick a plan. It's an expense like any other.