File for an LLC (or whatever legal entity is available to you locally), take your break, and when you're ready to come back put whatever you want under it for what you are interested in doing after the sabbatical.
LLC is good for legitimacy but is it supposed to look good on a resume or something?
Edit: Specifically curious if the LLC is supposed to fill-in as legit taxable paid work in-event-of-emergency or just gap-filler
Maybe you just did self study, but you did it as RealWork™ that your future employer will understand because they want SeriousPeople. It just allows you to drive the conversation the way you want to in a more controlled way. You could say Sole Proprietorship or Self Study, but I've found having an LLC is more receptive.