It's not that simple. Parsing isn't a problem, it's formatting with a timezone that sucks. It's a pinch point in a lot of different ways. Because MomentJS is in maintenance mode and the Temporal library isn't ready yet, I tried to do it in vanilla JS. Date objects don't do a good job of keeping track of timezone. You can only apply the timezone when converting the Date object to a string with .toLocaleString(locale, {timeZone: "America/New_York"}) and the formatting rules available are not capable of producing the desired not-quite-ISO8601Nanos timestamp (I don't want it to be in UTC, I want that layout with a trailing timezone offset). I fell back to moment but moment-timezone doesn't work well with the Jest tests as they're written. I plan to rewrite a lot when the Temporal library is prod ready but that won't be before this sprint is over.