No, there's no plan to do that. The trouble is that Luxon has no idea how the Hebrew calendar works; it only knows how to output the non-Gregorian stuff because your browser already can via the Intl.DateTimeFormat API. Luxon finds some interesting ways to abuse that API to add some neat features like internationalized parsing and full time zone support, but there's a limit there. To add 7 Hebrew months, Luxon would actually have to be able translate arbitrary Hebrew dates into timestamps, and I can't think of a way to make it do that without any real knowledge of the calendaring system.
The support for non-Gregorian output is interesting. Are there any plans to extend full support beyond Gregorian? For example, something like: