I’m not sure giving any newbie, elderly or not, a lithium-ion light is a good idea. Especially if that requires external charging. Most people will treat cells like they’re as safe as alkaline batteries. It’s just way too easy to short lithium-ion cells, and way more dangerous than shorting an alkaline.
There are 1xAA lights that will give you 500 lumens from an Eneloop. Most people would probably be amazed by that. Why give them the safety issues with lithium-ion lights, even if those LiFePO4 cells are slightly safer than the regular variant.
Plus, a NiMH light can use alkalines too, if they keep the brightness down to a moderate level.
If the person really wants a lithium-ion light, get one with built-in USB charging and low-voltage protection. Load a cell in it (a regular 4.2v cell is fine), and loctite the head and tail threads so it won’t come out.